diff --git a/ExternData/Resources/C-Sources/ED_INIFile.c b/ExternData/Resources/C-Sources/ED_INIFile.c
index 4287425a..3e499119 100644
--- a/ExternData/Resources/C-Sources/ED_INIFile.c
+++ b/ExternData/Resources/C-Sources/ED_INIFile.c
@@ -160,98 +160,128 @@ void ED_destroyINI(void* _ini)
 	}
 }
 
-double ED_getDoubleFromINI(void* _ini, const char* varName, const char* section)
+double ED_getDoubleFromINI(void* _ini, const char* varName, const char* section, int* exist)
 {
 	double ret = 0.;
 	INIFile* ini = (INIFile*)_ini;
+	*exist = 1;
 	if (ini != NULL) {
 		INISection* _section = findSection(ini, section);
 		if (_section != NULL) {
 			INIPair* pair = findKey(_section, varName);
 			if (pair != NULL) {
-				if (ED_strtod(pair->value, ini->loc, &ret)) {
-					ModelicaFormatError("Cannot read double value \"%s\" from file \"%s\"\n",
-						pair->value, ini->fileName);
+				if (NULL != pair->value) {
+					if (ED_strtod(pair->value, ini->loc, &ret)) {
+						ModelicaFormatError("Cannot read double value \"%s\" from file \"%s\"\n",
+							pair->value, ini->fileName);
+					}
+				}
+				else {
+					ModelicaFormatError("Cannot read value for key \"%s\" from file \"%s\"\n",
+						varName, ini->fileName);
+					*exist = 0;
 				}
 			}
 			else {
-				ModelicaFormatError("Cannot read key \"%s\" from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read key \"%s\" from file \"%s\"\n",
 					varName, ini->fileName);
+				*exist = 0;
 			}
 		}
 		else {
 			if (strlen(section) > 0) {
-				ModelicaFormatError("Cannot read section \"%s\" from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read section \"%s\" from file \"%s\"\n",
 					section, ini->fileName);
 			}
 			else {
-				ModelicaFormatError("Cannot read empty section from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read empty section from file \"%s\"\n",
 					ini->fileName);
 			}
+			*exist = 0;
 		}
 	}
 	return ret;
 }
 
-const char* ED_getStringFromINI(void* _ini, const char* varName, const char* section)
+const char* ED_getStringFromINI(void* _ini, const char* varName, const char* section, int* exist)
 {
 	INIFile* ini = (INIFile*)_ini;
+	*exist = 1;
 	if (ini != NULL) {
 		INISection* _section = findSection(ini, section);
 		if (_section != NULL) {
 			INIPair* pair = findKey(_section, varName);
 			if (pair != NULL) {
-				char* ret = ModelicaAllocateString(strlen(pair->value));
-				strcpy(ret, pair->value);
-				return (const char*)ret;
+				if (NULL != pair->value) {
+					char* ret = ModelicaAllocateString(strlen(pair->value));
+					strcpy(ret, pair->value);
+					return (const char*)ret;
+				}
+				else {
+					ModelicaFormatError("Cannot read value for key \"%s\" from file \"%s\"\n",
+						varName, ini->fileName);
+					*exist = 0;
+				}
 			}
 			else {
-				ModelicaFormatError("Cannot read key \"%s\" from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read key \"%s\" from file \"%s\"\n",
 					varName, ini->fileName);
+				*exist = 0;
 			}
 		}
 		else {
 			if (strlen(section) > 0) {
-				ModelicaFormatError("Cannot read section \"%s\" from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read section \"%s\" from file \"%s\"\n",
 					section, ini->fileName);
 			}
 			else {
-				ModelicaFormatError("Cannot read empty section from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read empty section from file \"%s\"\n",
 					ini->fileName);
 			}
+			*exist = 0;
 		}
 	}
 	return "";
 }
 
-int ED_getIntFromINI(void* _ini, const char* varName, const char* section)
+int ED_getIntFromINI(void* _ini, const char* varName, const char* section, int* exist)
 {
 	long ret = 0;
 	INIFile* ini = (INIFile*)_ini;
+	*exist = 1;
 	if (ini != NULL) {
 		INISection* _section = findSection(ini, section);
 		if (_section != NULL) {
 			INIPair* pair = findKey(_section, varName);
 			if (pair != NULL) {
-				if (ED_strtol(pair->value, ini->loc, &ret)) {
-					ModelicaFormatError("Cannot read int value \"%s\" from file \"%s\"\n",
-						pair->value, ini->fileName);
+				if (NULL != pair->value) {
+					if (ED_strtol(pair->value, ini->loc, &ret)) {
+						ModelicaFormatError("Cannot read int value \"%s\" from file \"%s\"\n",
+							pair->value, ini->fileName);
+					}
+				}
+				else {
+					ModelicaFormatError("Cannot read value for key \"%s\" from file \"%s\"\n",
+						varName, ini->fileName);
+					*exist = 0;
 				}
 			}
 			else {
-				ModelicaFormatError("Cannot read key \"%s\" from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read key \"%s\" from file \"%s\"\n",
 					varName, ini->fileName);
+				*exist = 0;
 			}
 		}
 		else {
 			if (strlen(section) > 0) {
-				ModelicaFormatError("Cannot read section \"%s\" from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read section \"%s\" from file \"%s\"\n",
 					section, ini->fileName);
 			}
 			else {
-				ModelicaFormatError("Cannot read empty section from file \"%s\"\n",
+				ModelicaFormatMessage("Cannot read empty section from file \"%s\"\n",
 					ini->fileName);
 			}
+			*exist = 0;
 		}
 	}
 	return (int)ret;
diff --git a/ExternData/Resources/C-Sources/ED_JSONFile.c b/ExternData/Resources/C-Sources/ED_JSONFile.c
index ad795d58..c22fee7d 100644
--- a/ExternData/Resources/C-Sources/ED_JSONFile.c
+++ b/ExternData/Resources/C-Sources/ED_JSONFile.c
@@ -116,40 +116,36 @@ static char* findValue(JsonNodeRef* root, const char* varName, const char* fileN
 	char* token = NULL;
 	char* buf = strdup(varName);
 	if (buf != NULL) {
-		int elementError = 0;
+		char* key = NULL;
 		char* nextToken = NULL;
 		token = strtok_r(buf, ".", &nextToken);
-		if (token == NULL) {
-			elementError = 1;
-		}
-		while (token != NULL && elementError == 0) {
-			size_t i;
-			int foundToken = 0;
-			for (i = 0; i < JsonNode_getChildCount(*root); i++) {
-				JsonNodeRef child = JsonNode_findChild(*root, token, JSON_OBJ);
-				if (child != NULL) {
-					*root = child;
-					token = strtok_r(NULL, ".", &nextToken);
-					foundToken = 1;
-					break;
-				}
+		while (token != NULL) {
+			JsonNodeRef iter = JsonNode_findChild(*root, token, JSON_OBJ);
+			if (NULL != iter) {
+				*root = iter;
+				token = strtok_r(NULL, ".", &nextToken);
 			}
-			if (foundToken == 0) {
-				elementError = 1;
+			else {
+				key = token;
+				token = strtok_r(NULL, ".", &nextToken);
+				break;
 			}
 		}
-		if (token == NULL) {
+		if (NULL != key && NULL != *root && NULL == token) {
+			token = JsonNode_getPairValue(*root, key);
 			free(buf);
-			ModelicaFormatError("Cannot read element \"%s\" from file \"%s\"\n",
-				varName, fileName);
+			if (NULL == token) {
+				ModelicaFormatMessage("Cannot read element \"%s\" from file \"%s\"\n",
+					varName, fileName);
+				*root = NULL;
+			}
 		}
 		else {
-			token = JsonNode_getPairValue(*root, token);
 			free(buf);
-			if (token == NULL) {
-				ModelicaFormatError("Cannot read element \"%s\" from file \"%s\"\n",
-					varName, fileName);
-			}
+			ModelicaFormatMessage("Cannot read element \"%s\" from file \"%s\"\n",
+				varName, fileName);
+			*root = NULL;
+			token = NULL;
 		}
 	}
 	else {
@@ -158,10 +154,11 @@ static char* findValue(JsonNodeRef* root, const char* varName, const char* fileN
 	return token;
 }
 
-double ED_getDoubleFromJSON(void* _json, const char* varName)
+double ED_getDoubleFromJSON(void* _json, const char* varName, int* exist)
 {
 	double ret = 0.;
 	JSONFile* json = (JSONFile*)_json;
+	*exist = 1;
 	if (json != NULL) {
 		JsonNodeRef root = json->root;
 		char* token = findValue(&root, varName, json->fileName);
@@ -171,17 +168,22 @@ double ED_getDoubleFromJSON(void* _json, const char* varName)
 					token, json->fileName);
 			}
 		}
-		else {
-			ModelicaFormatError("Cannot read double value from file \"%s\"\n",
+		else if (NULL != root) {
+			ModelicaFormatMessage("Cannot read double value from file \"%s\"\n",
 				json->fileName);
+			*exist = 0;
+		}
+		else {
+			*exist = 0;
 		}
 	}
 	return ret;
 }
 
-const char* ED_getStringFromJSON(void* _json, const char* varName)
+const char* ED_getStringFromJSON(void* _json, const char* varName, int* exist)
 {
 	JSONFile* json = (JSONFile*)_json;
+	*exist = 1;
 	if (json != NULL) {
 		JsonNodeRef root = json->root;
 		char* token = findValue(&root, varName, json->fileName);
@@ -190,18 +192,23 @@ const char* ED_getStringFromJSON(void* _json, const char* varName)
 			strcpy(ret, token);
 			return (const char*)ret;
 		}
-		else {
-			ModelicaFormatError("Cannot read value from file \"%s\"\n",
+		else if (NULL != root) {
+			ModelicaFormatMessage("Cannot read value from file \"%s\"\n",
 				json->fileName);
+			*exist = 0;
+		}
+		else {
+			*exist = 0;
 		}
 	}
 	return "";
 }
 
-int ED_getIntFromJSON(void* _json, const char* varName)
+int ED_getIntFromJSON(void* _json, const char* varName, int* exist)
 {
 	long ret = 0;
 	JSONFile* json = (JSONFile*)_json;
+	*exist = 1;
 	if (json != NULL) {
 		JsonNodeRef root = json->root;
 		char* token = findValue(&root, varName, json->fileName);
@@ -211,9 +218,13 @@ int ED_getIntFromJSON(void* _json, const char* varName)
 					token, json->fileName);
 			}
 		}
-		else {
-			ModelicaFormatError("Cannot read int value from file \"%s\"\n",
+		else if (NULL != root) {
+			ModelicaFormatMessage("Cannot read int value from file \"%s\"\n",
 				json->fileName);
+			*exist = 0;
+		}
+		else {
+			*exist = 0;
 		}
 	}
 	return (int)ret;
diff --git a/ExternData/Resources/C-Sources/ED_XLSFile.c b/ExternData/Resources/C-Sources/ED_XLSFile.c
index c26982ae..25d6c914 100644
--- a/ExternData/Resources/C-Sources/ED_XLSFile.c
+++ b/ExternData/Resources/C-Sources/ED_XLSFile.c
@@ -150,7 +150,7 @@ static xlsWorkSheet* findSheet(XLSFile* xls, char** sheetName)
 			}
 		}
 		if (sheet < 0) {
-			ModelicaFormatError("Cannot find sheet \"%s\" in file \"%s\"\n",
+			ModelicaFormatMessage("Cannot find sheet \"%s\" in file \"%s\"\n",
 				*sheetName, xls->fileName);
 			return NULL;
 		}
@@ -167,97 +167,172 @@ static xlsWorkSheet* findSheet(XLSFile* xls, char** sheetName)
 	return pWS;
 }
 
-double ED_getDoubleFromXLS(void* _xls, const char* cellAddress, const char* sheetName)
+double ED_getDoubleFromXLS(void* _xls, const char* cellAddress, const char* sheetName, int* exist)
 {
 	double ret = 0.;
-	ED_getDoubleArray2DFromXLS(_xls, cellAddress, sheetName, &ret, 1, 1);
+	XLSFile* xls = (XLSFile*)_xls;
+	*exist = 1;
+	if (xls != NULL) {
+		char* _sheetName = (char*)sheetName;
+		xlsWorkSheet* pWS = findSheet(xls, &_sheetName);
+		if (NULL != pWS) {
+			xlsCell* cell;
+			WORD row = 0, col = 0;
+
+			rc(cellAddress, &row, &col);
+			cell = xls_cell(pWS, row, col);
+			if (cell != NULL && !cell->isHidden) {
+				/* Get the value of the cell (either numeric or string) */
+				if (cell->id == XLS_RECORD_RK || cell->id == XLS_RECORD_MULRK || cell->id == XLS_RECORD_NUMBER) {
+					ret = cell->d;
+				}
+				else if (cell->id == XLS_RECORD_FORMULA) {
+					if (cell->l == 0) { /* It is a number */
+						ret = cell->d;
+					}
+					else {
+						if (0 == strcmp((char*)cell->str, "bool")) { /* It is boolean */
+							ret = (int)cell->d ? 1. : 0.;
+						}
+						else if (0 == strcmp((char*)cell->str, "error")) { /* Formula is in error */
+							ModelicaFormatError("Error in formula of cell (%u,%u) in sheet \"%s\" of file \"%s\"\n",
+								(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+						}
+						else { /* Valid formula result */
+							if (ED_strtod((char*)cell->str, xls->loc, &ret)) {
+								ModelicaFormatError("Error in cell (%u,%u) when reading double value \"%s\" from sheet \"%s\" of file \"%s\"\n",
+									(unsigned int)row, (unsigned int)col, cell->str, _sheetName, xls->fileName);
+							}
+						}
+					}
+				}
+				else if (cell->str != NULL) {
+					if (ED_strtod((char*)cell->str, xls->loc, &ret)) {
+						ModelicaFormatError("Error in cell (%u,%u) when reading double value \"%s\" from sheet \"%s\" of file \"%s\"\n",
+							(unsigned int)row, (unsigned int)col, cell->str, _sheetName, xls->fileName);
+					}
+				}
+				else {
+					*exist = 0;
+				}
+			}
+			else {
+				ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
+					(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+				*exist = 0;
+			}
+		}
+		else {
+			*exist = 0;
+		}
+	}
 	return ret;
 }
 
-const char* ED_getStringFromXLS(void* _xls, const char* cellAddress, const char* sheetName)
+const char* ED_getStringFromXLS(void* _xls, const char* cellAddress, const char* sheetName, int* exist)
 {
 	XLSFile* xls = (XLSFile*)_xls;
+	*exist = 1;
 	if (xls != NULL) {
 		char* _sheetName = (char*)sheetName;
 		xlsWorkSheet* pWS = findSheet(xls, &_sheetName);
-		xlsCell* cell;
-		WORD row = 0, col = 0;
+		if (NULL != pWS) {
+			xlsCell* cell;
+			WORD row = 0, col = 0;
 
-		rc(cellAddress, &row, &col);
-		cell = xls_cell(pWS, row, col);
-		if (cell != NULL && !cell->isHidden) {
-			/* Get the string value of the cell */
-			if (cell->id == XLS_RECORD_FORMULA) {
-				if (cell->l != 0) { /* It is not a number */
-					if ((0 != strcmp((char*)cell->str, "bool")) && /* It is not boolean and */
-						(0 != strcmp((char*)cell->str, "error"))) { /* formula is not in error */
-						char* ret = ModelicaAllocateString(strlen((char*)cell->str));
-						strcpy(ret, (char*)cell->str);
-						return (const char*)ret;
+			rc(cellAddress, &row, &col);
+			cell = xls_cell(pWS, row, col);
+			if (cell != NULL && !cell->isHidden) {
+				/* Get the string value of the cell */
+				if (cell->id == XLS_RECORD_FORMULA) {
+					if (cell->l != 0) { /* It is not a number */
+						if ((0 != strcmp((char*)cell->str, "bool")) && /* It is not boolean and */
+							(0 != strcmp((char*)cell->str, "error"))) { /* formula is not in error */
+							char* ret = ModelicaAllocateString(strlen((char*)cell->str));
+							strcpy(ret, (char*)cell->str);
+							return (const char*)ret;
+						}
 					}
 				}
+				else if (cell->str != NULL) {
+					char* ret = ModelicaAllocateString(strlen((char*)cell->str));
+					strcpy(ret, (char*)cell->str);
+					return (const char*)ret;
+				}
+				else {
+					*exist = 0;
+				}
 			}
-			else if (cell->str != NULL) {
-				char* ret = ModelicaAllocateString(strlen((char*)cell->str));
-				strcpy(ret, (char*)cell->str);
-				return (const char*)ret;
+			else {
+				ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
+					(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+				*exist = 0;
 			}
 		}
 		else {
-			ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
-				(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+			*exist = 0;
 		}
 	}
 	return "";
 }
 
-int ED_getIntFromXLS(void* _xls, const char* cellAddress, const char* sheetName)
+int ED_getIntFromXLS(void* _xls, const char* cellAddress, const char* sheetName, int* exist)
 {
 	long ret = 0;
 	XLSFile* xls = (XLSFile*)_xls;
+	*exist = 1;
 	if (xls != NULL) {
 		char* _sheetName = (char*)sheetName;
 		xlsWorkSheet* pWS = findSheet(xls, &_sheetName);
-		xlsCell* cell;
-		WORD row = 0, col = 0;
+		if (NULL != pWS) {
+			xlsCell* cell;
+			WORD row = 0, col = 0;
 
-		rc(cellAddress, &row, &col);
-		cell = xls_cell(pWS, row, col);
-		if (cell != NULL && !cell->isHidden) {
-			/* Get the value of the cell (either numeric or string) */
-			if (cell->id == XLS_RECORD_RK || cell->id == XLS_RECORD_MULRK || cell->id == XLS_RECORD_NUMBER) {
-				ret = (long)cell->d;
-			}
-			else if (cell->id == XLS_RECORD_FORMULA) {
-				if (cell->l == 0) { /* It is a number */
+			rc(cellAddress, &row, &col);
+			cell = xls_cell(pWS, row, col);
+			if (cell != NULL && !cell->isHidden) {
+				/* Get the value of the cell (either numeric or string) */
+				if (cell->id == XLS_RECORD_RK || cell->id == XLS_RECORD_MULRK || cell->id == XLS_RECORD_NUMBER) {
 					ret = (long)cell->d;
 				}
-				else {
-					if (0 == strcmp((char*)cell->str, "bool")) { /* It is boolean */
-						ret = (long)cell->d ? 1 : 0;
-					}
-					else if (0 == strcmp((char*)cell->str, "error")) { /* Formula is in error */
-						ModelicaFormatError("Error in formula of cell (%u,%u) in sheet \"%s\" of file \"%s\"\n",
-							(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+				else if (cell->id == XLS_RECORD_FORMULA) {
+					if (cell->l == 0) { /* It is a number */
+						ret = (long)cell->d;
 					}
-					else { /* Valid formula result */
-						if (ED_strtol((char*)cell->str, xls->loc, &ret)) {
-							ModelicaFormatError("Error in cell (%u,%u) when reading int value \"%s\" from sheet \"%s\" of file \"%s\"\n",
-								(unsigned int)row, (unsigned int)col, (char*)cell->str, _sheetName, xls->fileName);
+					else {
+						if (0 == strcmp((char*)cell->str, "bool")) { /* It is boolean */
+							ret = (long)cell->d ? 1 : 0;
+						}
+						else if (0 == strcmp((char*)cell->str, "error")) { /* Formula is in error */
+							ModelicaFormatError("Error in formula of cell (%u,%u) in sheet \"%s\" of file \"%s\"\n",
+								(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+						}
+						else { /* Valid formula result */
+							if (ED_strtol((char*)cell->str, xls->loc, &ret)) {
+								ModelicaFormatError("Error in cell (%u,%u) when reading int value \"%s\" from sheet \"%s\" of file \"%s\"\n",
+									(unsigned int)row, (unsigned int)col, (char*)cell->str, _sheetName, xls->fileName);
+							}
 						}
 					}
 				}
-			}
-			else if (cell->str != NULL) {
-				if (ED_strtol((char*)cell->str, xls->loc, &ret)) {
-					ModelicaFormatError("Error in cell (%u,%u) when reading int value \"%s\" from sheet \"%s\" of file \"%s\"\n",
-						(unsigned int)row, (unsigned int)col, (char*)cell->str, _sheetName, xls->fileName);
+				else if (cell->str != NULL) {
+					if (ED_strtol((char*)cell->str, xls->loc, &ret)) {
+						ModelicaFormatError("Error in cell (%u,%u) when reading int value \"%s\" from sheet \"%s\" of file \"%s\"\n",
+							(unsigned int)row, (unsigned int)col, (char*)cell->str, _sheetName, xls->fileName);
+					}
 				}
+				else {
+					*exist = 0;
+				}
+			}
+			else {
+				ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
+					(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+				*exist = 0;
 			}
 		}
 		else {
-			ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
-				(unsigned int)row, (unsigned int)col, _sheetName, xls->fileName);
+			*exist = 0;
 		}
 	}
 	return (int)ret;
@@ -269,49 +344,51 @@ void ED_getDoubleArray2DFromXLS(void* _xls, const char* cellAddress, const char*
 	if (xls != NULL) {
 		char* _sheetName = (char*)sheetName;
 		xlsWorkSheet* pWS = findSheet(xls, &_sheetName);
-		WORD row = 0, col = 0;
-		WORD i, j;
+		if (NULL != pWS) {
+			WORD row = 0, col = 0;
+			WORD i, j;
 
-		rc(cellAddress, &row, &col);
-		for (i = 0; i < m; i++) {
-			for (j = 0; j < n; j++) {
-				xlsCell* cell = xls_cell(pWS, row + i, col + j);
-				if (cell != NULL && !cell->isHidden) {
-					/* Get the value of the cell (either numeric or string) */
-					if (cell->id == XLS_RECORD_RK || cell->id == XLS_RECORD_MULRK || cell->id == XLS_RECORD_NUMBER) {
-						a[i*n + j] = cell->d;
-					}
-					else if (cell->id == XLS_RECORD_FORMULA) {
-						if (cell->l == 0) { /* It is a number */
+			rc(cellAddress, &row, &col);
+			for (i = 0; i < m; i++) {
+				for (j = 0; j < n; j++) {
+					xlsCell* cell = xls_cell(pWS, row + i, col + j);
+					if (cell != NULL && !cell->isHidden) {
+						/* Get the value of the cell (either numeric or string) */
+						if (cell->id == XLS_RECORD_RK || cell->id == XLS_RECORD_MULRK || cell->id == XLS_RECORD_NUMBER) {
 							a[i*n + j] = cell->d;
 						}
-						else {
-							if (0 == strcmp((char*)cell->str, "bool")) { /* It is boolean */
-								a[i*n + j] = (int)cell->d ? 1. : 0.;
+						else if (cell->id == XLS_RECORD_FORMULA) {
+							if (cell->l == 0) { /* It is a number */
+								a[i*n + j] = cell->d;
 							}
-							else if (0 == strcmp((char*)cell->str, "error")) { /* Formula is in error */
-								ModelicaFormatError("Error in formula of cell (%u,%u) in sheet \"%s\" of file \"%s\"\n",
-									(unsigned int)(row + i), (unsigned int)(col + j), _sheetName, xls->fileName);
-							}
-							else { /* Valid formula result */
-								if (ED_strtod((char*)cell->str, xls->loc, &a[i*n + j])) {
-									ModelicaFormatError("Error in cell (%u,%u) when reading double value \"%s\" from sheet \"%s\" of file \"%s\"\n",
-										(unsigned int)(row + i), (unsigned int)(col + j), cell->str, _sheetName, xls->fileName);
+							else {
+								if (0 == strcmp((char*)cell->str, "bool")) { /* It is boolean */
+									a[i*n + j] = (int)cell->d ? 1. : 0.;
+								}
+								else if (0 == strcmp((char*)cell->str, "error")) { /* Formula is in error */
+									ModelicaFormatError("Error in formula of cell (%u,%u) in sheet \"%s\" of file \"%s\"\n",
+										(unsigned int)(row + i), (unsigned int)(col + j), _sheetName, xls->fileName);
+								}
+								else { /* Valid formula result */
+									if (ED_strtod((char*)cell->str, xls->loc, &a[i*n + j])) {
+										ModelicaFormatError("Error in cell (%u,%u) when reading double value \"%s\" from sheet \"%s\" of file \"%s\"\n",
+											(unsigned int)(row + i), (unsigned int)(col + j), cell->str, _sheetName, xls->fileName);
+									}
 								}
 							}
 						}
-					}
-					else if (cell->str != NULL) {
-						if (ED_strtod((char*)cell->str, xls->loc, &a[i*n + j])) {
-							ModelicaFormatError("Error in cell (%u,%u) when reading double value \"%s\" from sheet \"%s\" of file \"%s\"\n",
-								(unsigned int)(row + i), (unsigned int)(col + j), cell->str, _sheetName, xls->fileName);
+						else if (cell->str != NULL) {
+							if (ED_strtod((char*)cell->str, xls->loc, &a[i*n + j])) {
+								ModelicaFormatError("Error in cell (%u,%u) when reading double value \"%s\" from sheet \"%s\" of file \"%s\"\n",
+									(unsigned int)(row + i), (unsigned int)(col + j), cell->str, _sheetName, xls->fileName);
+							}
 						}
 					}
-				}
-				else {
-					a[i*n + j] = 0.;
-					ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
-						(unsigned int)(row + i), (unsigned int)(col + j), _sheetName, xls->fileName);
+					else {
+						a[i*n + j] = 0.;
+						ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
+							(unsigned int)(row + i), (unsigned int)(col + j), _sheetName, xls->fileName);
+					}
 				}
 			}
 		}
diff --git a/ExternData/Resources/C-Sources/ED_XLSXFile.c b/ExternData/Resources/C-Sources/ED_XLSXFile.c
index 63a65889..e377c246 100644
--- a/ExternData/Resources/C-Sources/ED_XLSXFile.c
+++ b/ExternData/Resources/C-Sources/ED_XLSXFile.c
@@ -266,7 +266,7 @@ static XmlNodeRef findSheet(XLSXFile* xlsx, char** sheetName)
 
 	HASH_FIND_STR(xlsx->sheets, *sheetName, iter);
 	if (iter == NULL) {
-		ModelicaFormatError("Cannot find sheet name \"%s\" in file \"%s\" of file \"%s\"\n",
+		ModelicaFormatMessage("Cannot find sheet name \"%s\" in file \"%s\" of file \"%s\"\n",
 			*sheetName, WB_XML, xlsx->fileName);
 		return NULL;
 	}
@@ -369,10 +369,11 @@ static char* findCellValue(XLSXFile* xlsx, const char* cellAddress, XmlNodeRef r
 	return token;
 }
 
-double ED_getDoubleFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName)
+double ED_getDoubleFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName, int* exist)
 {
 	double ret = 0.;
 	XLSXFile* xlsx = (XLSXFile*)_xlsx;
+	*exist = 1;
 	if (xlsx != NULL) {
 		char* _sheetName = (char*)sheetName;
 		XmlNodeRef root = findSheet(xlsx, &_sheetName);
@@ -389,15 +390,20 @@ double ED_getDoubleFromXLSX(void* _xlsx, const char* cellAddress, const char* sh
 				rc(cellAddress, &row, &col);
 				ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
 					(unsigned int)row, (unsigned int)col, sheetName, xlsx->fileName);
+				*exist = 0;
 			}
 		}
+		else {
+			*exist = 0;
+		}
 	}
 	return ret;
 }
 
-const char* ED_getStringFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName)
+const char* ED_getStringFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName, int* exist)
 {
 	XLSXFile* xlsx = (XLSXFile*)_xlsx;
+	*exist = 1;
 	if (xlsx != NULL) {
 		char* _sheetName = (char*)sheetName;
 		XmlNodeRef root = findSheet(xlsx, &_sheetName);
@@ -413,16 +419,21 @@ const char* ED_getStringFromXLSX(void* _xlsx, const char* cellAddress, const cha
 				rc(cellAddress, &row, &col);
 				ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
 					(unsigned int)row, (unsigned int)col, sheetName, xlsx->fileName);
+				*exist = 0;
 			}
 		}
+		else {
+			*exist = 0;
+		}
 	}
 	return "";
 }
 
-int ED_getIntFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName)
+int ED_getIntFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName, int* exist)
 {
 	long ret = 0;
 	XLSXFile* xlsx = (XLSXFile*)_xlsx;
+	*exist = 1;
 	if (xlsx != NULL) {
 		char* _sheetName = (char*)sheetName;
 		XmlNodeRef root = findSheet(xlsx, &_sheetName);
@@ -439,8 +450,12 @@ int ED_getIntFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetNam
 				rc(cellAddress, &row, &col);
 				ModelicaFormatMessage("Cannot get cell (%u,%u) in sheet \"%s\" from file \"%s\"\n",
 					(unsigned int)row, (unsigned int)col, sheetName, xlsx->fileName);
+				*exist = 0;
 			}
 		}
+		else {
+			*exist = 0;
+		}
 	}
 	return (int)ret;
 }
diff --git a/ExternData/Resources/C-Sources/ED_XMLFile.c b/ExternData/Resources/C-Sources/ED_XMLFile.c
index 5f9f3790..921b4670 100644
--- a/ExternData/Resources/C-Sources/ED_XMLFile.c
+++ b/ExternData/Resources/C-Sources/ED_XMLFile.c
@@ -123,27 +123,25 @@ static char* findValue(XmlNodeRef* root, const char* varName, const char* fileNa
 			elementError = 1;
 		}
 		while (token != NULL && elementError == 0) {
-			size_t i;
-			int foundToken = 0;
-			for (i = 0; i < XmlNode_getChildCount(*root); i++) {
-				XmlNodeRef child = XmlNode_getChild(*root, i);
-				if (XmlNode_isTag(child, token)) {
-					*root = child;
-					token = strtok_r(NULL, ".", &nextToken);
-					foundToken = 1;
-					break;
-				}
+			XmlNodeRef iter = XmlNode_findChild(*root, token);
+			if (NULL != iter) {
+				*root = iter;
+				token = strtok_r(NULL, ".", &nextToken);
 			}
-			if (foundToken == 0) {
+			else {
 				elementError = 1;
 			}
 		}
 		free(buf);
-		if (elementError == 1) {
-			ModelicaFormatError("Error in line %i: Cannot find element \"%s\" in file \"%s\"\n",
+		if (0 == elementError) {
+			XmlNode_getValue(*root, &token);
+		}
+		else {
+			ModelicaFormatMessage("Error in line %i: Cannot find element \"%s\" in file \"%s\"\n",
 				XmlNode_getLine(*root), varName, fileName);
+			*root = NULL;
+			token = NULL;
 		}
-		XmlNode_getValue(*root, &token);
 	}
 	else {
 		ModelicaError("Memory allocation error\n");
@@ -151,10 +149,11 @@ static char* findValue(XmlNodeRef* root, const char* varName, const char* fileNa
 	return token;
 }
 
-double ED_getDoubleFromXML(void* _xml, const char* varName)
+double ED_getDoubleFromXML(void* _xml, const char* varName, int* exist)
 {
 	double ret = 0.;
 	XMLFile* xml = (XMLFile*)_xml;
+	*exist = 1;
 	if (xml != NULL) {
 		XmlNodeRef root = xml->root;
 		char* token = findValue(&root, varName, xml->fileName);
@@ -164,17 +163,22 @@ double ED_getDoubleFromXML(void* _xml, const char* varName)
 					XmlNode_getLine(root), token, xml->fileName);
 			}
 		}
-		else {
-			ModelicaFormatError("Error in line %i: Cannot read double value from file \"%s\"\n",
+		else if (NULL != root) {
+			ModelicaFormatMessage("Error in line %i: Cannot read double value from file \"%s\"\n",
 				XmlNode_getLine(root), xml->fileName);
+			*exist = 0;
+		}
+		else {
+			*exist = 0;
 		}
 	}
 	return ret;
 }
 
-const char* ED_getStringFromXML(void* _xml, const char* varName)
+const char* ED_getStringFromXML(void* _xml, const char* varName, int* exist)
 {
 	XMLFile* xml = (XMLFile*)_xml;
+	*exist = 1;
 	if (xml != NULL) {
 		XmlNodeRef root = xml->root;
 		char* token = findValue(&root, varName, xml->fileName);
@@ -183,18 +187,23 @@ const char* ED_getStringFromXML(void* _xml, const char* varName)
 			strcpy(ret, token);
 			return (const char*)ret;
 		}
-		else {
-			ModelicaFormatError("Error in line %i: Cannot read value from file \"%s\"\n",
+		else if (NULL != root) {
+			ModelicaFormatMessage("Error in line %i: Cannot read value from file \"%s\"\n",
 				XmlNode_getLine(root), xml->fileName);
+			*exist = 0;
+		}
+		else {
+			*exist = 0;
 		}
 	}
 	return "";
 }
 
-int ED_getIntFromXML(void* _xml, const char* varName)
+int ED_getIntFromXML(void* _xml, const char* varName, int* exist)
 {
 	long ret = 0;
 	XMLFile* xml = (XMLFile*)_xml;
+	*exist = 1;
 	if (xml != NULL) {
 		XmlNodeRef root = xml->root;
 		char* token = findValue(&root, varName, xml->fileName);
@@ -204,9 +213,13 @@ int ED_getIntFromXML(void* _xml, const char* varName)
 					XmlNode_getLine(root), token, xml->fileName);
 			}
 		}
-		else {
-			ModelicaFormatError("Error in line %i: Cannot read int value from file \"%s\"\n",
+		else if (NULL != root) {
+			ModelicaFormatMessage("Error in line %i: Cannot read int value from file \"%s\"\n",
 				XmlNode_getLine(root), xml->fileName);
+			*exist = 0;
+		}
+		else {
+			*exist = 0;
 		}
 	}
 	return (int)ret;
diff --git a/ExternData/Resources/Include/ED_INIFile.h b/ExternData/Resources/Include/ED_INIFile.h
index d07aba60..f8d1746c 100644
--- a/ExternData/Resources/Include/ED_INIFile.h
+++ b/ExternData/Resources/Include/ED_INIFile.h
@@ -31,8 +31,8 @@
 
 void* ED_createINI(const char* fileName, int verbose);
 void ED_destroyINI(void* _ini);
-double ED_getDoubleFromINI(void* _ini, const char* varName, const char* section);
-const char* ED_getStringFromINI(void* _ini, const char* varName, const char* section);
-int ED_getIntFromINI(void* _ini, const char* varName, const char* section);
+double ED_getDoubleFromINI(void* _ini, const char* varName, const char* section, int* exist);
+const char* ED_getStringFromINI(void* _ini, const char* varName, const char* section, int* exist);
+int ED_getIntFromINI(void* _ini, const char* varName, const char* section, int* exist);
 
 #endif
diff --git a/ExternData/Resources/Include/ED_JSONFile.h b/ExternData/Resources/Include/ED_JSONFile.h
index bdfda180..7f4938d8 100644
--- a/ExternData/Resources/Include/ED_JSONFile.h
+++ b/ExternData/Resources/Include/ED_JSONFile.h
@@ -31,8 +31,8 @@
 
 void* ED_createJSON(const char* fileName, int verbose);
 void ED_destroyJSON(void* _json);
-double ED_getDoubleFromJSON(void* _json, const char* varName);
-const char* ED_getStringFromJSON(void* _json, const char* varName);
-int ED_getIntFromJSON(void* _json, const char* varName);
+double ED_getDoubleFromJSON(void* _json, const char* varName, int* exist);
+const char* ED_getStringFromJSON(void* _json, const char* varName, int* exist);
+int ED_getIntFromJSON(void* _json, const char* varName, int* exist);
 
 #endif
diff --git a/ExternData/Resources/Include/ED_XLSFile.h b/ExternData/Resources/Include/ED_XLSFile.h
index e4520e3e..df5e416c 100644
--- a/ExternData/Resources/Include/ED_XLSFile.h
+++ b/ExternData/Resources/Include/ED_XLSFile.h
@@ -31,9 +31,9 @@
 
 void* ED_createXLS(const char* fileName, const char* encoding, int verbose);
 void ED_destroyXLS(void* _xls);
-double ED_getDoubleFromXLS(void* _xls, const char* cellAddress, const char* sheetName);
-const char* ED_getStringFromXLS(void* _xls, const char* cellAddress, const char* sheetName);
-int ED_getIntFromXLS(void* _xls, const char* cellAddress, const char* sheetName);
+double ED_getDoubleFromXLS(void* _xls, const char* cellAddress, const char* sheetName, int* exist);
+const char* ED_getStringFromXLS(void* _xls, const char* cellAddress, const char* sheetName, int* exist);
+int ED_getIntFromXLS(void* _xls, const char* cellAddress, const char* sheetName, int* exist);
 void ED_getDoubleArray2DFromXLS(void* _xls, const char* cellAddress, const char* sheetName, double* a, size_t m, size_t n);
 
 #endif
diff --git a/ExternData/Resources/Include/ED_XLSXFile.h b/ExternData/Resources/Include/ED_XLSXFile.h
index 2c262e08..46aa9ae3 100644
--- a/ExternData/Resources/Include/ED_XLSXFile.h
+++ b/ExternData/Resources/Include/ED_XLSXFile.h
@@ -31,9 +31,9 @@
 
 void* ED_createXLSX(const char* fileName, int verbose);
 void ED_destroyXLSX(void* _xlsx);
-double ED_getDoubleFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName);
-const char* ED_getStringFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName);
-int ED_getIntFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName);
+double ED_getDoubleFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName, int* exist);
+const char* ED_getStringFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName, int* exist);
+int ED_getIntFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName, int* exist);
 void ED_getDoubleArray2DFromXLSX(void* _xlsx, const char* cellAddress, const char* sheetName, double* a, size_t m, size_t n);
 
 #endif
diff --git a/ExternData/Resources/Include/ED_XMLFile.h b/ExternData/Resources/Include/ED_XMLFile.h
index 27689738..2232b369 100644
--- a/ExternData/Resources/Include/ED_XMLFile.h
+++ b/ExternData/Resources/Include/ED_XMLFile.h
@@ -32,9 +32,9 @@
 
 void* ED_createXML(const char* fileName, int verbose);
 void ED_destroyXML(void* _xml);
-double ED_getDoubleFromXML(void* _xml, const char* varName);
-const char* ED_getStringFromXML(void* _xml, const char* varName);
-int ED_getIntFromXML(void* _xml, const char* varName);
+double ED_getDoubleFromXML(void* _xml, const char* varName, int* exist);
+const char* ED_getStringFromXML(void* _xml, const char* varName, int* exist);
+int ED_getIntFromXML(void* _xml, const char* varName, int* exist);
 void ED_getDoubleArray1DFromXML(void* _xml, const char* varName, double* a, size_t n);
 void ED_getDoubleArray2DFromXML(void* _xml, const char* varName, double* a, size_t m, size_t n);
 
diff --git a/ExternData/package.mo b/ExternData/package.mo
index e66f7621..8679d4b7 100644
--- a/ExternData/package.mo
+++ b/ExternData/package.mo
@@ -270,7 +270,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         extends Interfaces.partialGetReal;
         input String section="" "Section";
         input Types.ExternINIFile ini "External INI file object";
-        external "C" y=ED_getDoubleFromINI(ini, varName, section) annotation(
+        external "C" y=ED_getDoubleFromINI(ini, varName, section, exist) annotation(
           __iti_dll = "ITI_ED_INIFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_INIFile.h\"",
@@ -281,7 +281,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         extends Interfaces.partialGetInteger;
         input String section="" "Section";
         input Types.ExternINIFile ini "External INI file object";
-        external "C" y=ED_getIntFromINI(ini, varName, section) annotation(
+        external "C" y=ED_getIntFromINI(ini, varName, section, exist) annotation(
           __iti_dll = "ITI_ED_INIFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_INIFile.h\"",
@@ -292,8 +292,11 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         extends Interfaces.partialGetBoolean;
         input String section="" "Section";
         input Types.ExternINIFile ini "External INI file object";
+        protected
+          Real aux;
         algorithm
-          y := getReal(ini=ini, varName=varName, section=section) <> 0;
+          (aux, exist) := getReal(ini=ini, varName=varName, section=section);
+          y := aux <> 0;
         annotation(Inline=true);
       end getBoolean;
 
@@ -301,7 +304,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         extends Interfaces.partialGetString;
         input String section="" "Section";
         input Types.ExternINIFile ini "External INI file object";
-        external "C" str=ED_getStringFromINI(ini, varName, section) annotation(
+        external "C" str=ED_getStringFromINI(ini, varName, section, exist) annotation(
           __iti_dll = "ITI_ED_INIFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_INIFile.h\"",
@@ -315,7 +318,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
       function getReal "Get scalar Real value from JSON file"
         extends Interfaces.partialGetReal;
         input Types.ExternJSONFile json "External JSON file object";
-        external "C" y=ED_getDoubleFromJSON(json, varName) annotation(
+        external "C" y=ED_getDoubleFromJSON(json, varName, exist) annotation(
           __iti_dll = "ITI_ED_JSONFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_JSONFile.h\"",
@@ -325,7 +328,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
       function getInteger "Get scalar Integer value from JSON file"
         extends Interfaces.partialGetInteger;
         input Types.ExternJSONFile json "External JSON file object";
-        external "C" y=ED_getIntFromJSON(json, varName) annotation(
+        external "C" y=ED_getIntFromJSON(json, varName, exist) annotation(
           __iti_dll = "ITI_ED_JSONFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_JSONFile.h\"",
@@ -343,7 +346,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
       function getString "Get scalar String value from JSON file"
         extends Interfaces.partialGetString;
         input Types.ExternJSONFile json "External JSON file object";
-        external "C" str=ED_getStringFromJSON(json, varName) annotation(
+        external "C" str=ED_getStringFromJSON(json, varName, exist) annotation(
           __iti_dll = "ITI_ED_JSONFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_JSONFile.h\"",
@@ -391,7 +394,8 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSFile xls "External Excel XLS file object";
         output Real y "Real value";
-        external "C" y=ED_getDoubleFromXLS(xls, cellAddress, sheetName) annotation(
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set to 0.0";
+        external "C" y=ED_getDoubleFromXLS(xls, cellAddress, sheetName, exist) annotation(
           __iti_dll = "ITI_ED_XLSFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XLSFile.h\"",
@@ -419,7 +423,8 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSFile xls "External Excel XLS file object";
         output Integer y "Integer value";
-        external "C" y=ED_getIntFromXLS(xls, cellAddress, sheetName) annotation(
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set to 0";
+        external "C" y=ED_getIntFromXLS(xls, cellAddress, sheetName, exist) annotation(
           __iti_dll = "ITI_ED_XLSFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XLSFile.h\"",
@@ -432,8 +437,12 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSFile xls "External Excel XLS file object";
         output Boolean y "Boolean value";
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set to false";
+        protected
+          Real aux;
         algorithm
-          y := getReal(xls=xls, cellAddress=cellAddress, sheetName=sheetName) <> 0;
+          (aux, exist) := getReal(xls=xls, cellAddress=cellAddress, sheetName=sheetName);
+          y := aux <> 0;
         annotation(Inline=true);
       end getBoolean;
 
@@ -443,7 +452,8 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSFile xls "External Excel XLS file object";
         output String str "String value";
-        external "C" str=ED_getStringFromXLS(xls, cellAddress, sheetName) annotation(
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set to an empty string";
+        external "C" str=ED_getStringFromXLS(xls, cellAddress, sheetName, exist) annotation(
           __iti_dll = "ITI_ED_XLSFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XLSFile.h\"",
@@ -460,7 +470,8 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSXFile xlsx "External Excel XLSX file object";
         output Real y "Real value";
-        external "C" y=ED_getDoubleFromXLSX(xlsx, cellAddress, sheetName) annotation(
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set to 0.0";
+        external "C" y=ED_getDoubleFromXLSX(xlsx, cellAddress, sheetName, exist) annotation(
           __iti_dll = "ITI_ED_XLSXFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XLSXFile.h\"",
@@ -488,7 +499,8 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSXFile xlsx "External Excel XLSX file object";
         output Integer y "Integer value";
-        external "C" y=ED_getIntFromXLSX(xlsx, cellAddress, sheetName) annotation(
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set 0";
+        external "C" y=ED_getIntFromXLSX(xlsx, cellAddress, sheetName, true) annotation(
           __iti_dll = "ITI_ED_XLSXFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XLSXFile.h\"",
@@ -501,8 +513,12 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSXFile xlsx "External Excel XLSX file object";
         output Boolean y "Boolean value";
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set to false";
+        protected
+          Real aux;
         algorithm
-          y := getReal(xlsx=xlsx, cellAddress=cellAddress, sheetName=sheetName) <> 0;
+          (aux, exist) := getReal(xlsx=xlsx, cellAddress=cellAddress, sheetName=sheetName);
+          y := aux <> 0;
         annotation(Inline=true);
       end getBoolean;
 
@@ -512,7 +528,8 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
         input String sheetName="" "Sheet name";
         input Types.ExternXLSXFile xlsx "External Excel XLSX file object";
         output String str "String value";
-        external "C" str=ED_getStringFromXLSX(xlsx, cellAddress, sheetName) annotation(
+        output Boolean exist "= true, if cellAddress exits; = false, if it does not exist and y is set to an empty string";
+        external "C" str=ED_getStringFromXLSX(xlsx, cellAddress, sheetName, exist) annotation(
           __iti_dll = "ITI_ED_XLSXFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XLSXFile.h\"",
@@ -526,7 +543,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
       function getReal "Get scalar Real value from XML file"
         extends Interfaces.partialGetReal;
         input Types.ExternXMLFile xml "External XML file object";
-        external "C" y=ED_getDoubleFromXML(xml, varName) annotation(
+        external "C" y=ED_getDoubleFromXML(xml, varName, exist) annotation(
           __iti_dll = "ITI_ED_XMLFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XMLFile.h\"",
@@ -563,7 +580,7 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
       function getInteger "Get scalar Integer value from XML file"
         extends Interfaces.partialGetInteger;
         input Types.ExternXMLFile xml "External XML file object";
-        external "C" y=ED_getIntFromXML(xml, varName) annotation(
+        external "C" y=ED_getIntFromXML(xml, varName, exist) annotation(
           __iti_dll = "ITI_ED_XMLFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XMLFile.h\"",
@@ -573,15 +590,18 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
       function getBoolean "Get scalar Boolean value from XML file"
         extends Interfaces.partialGetBoolean;
         input Types.ExternXMLFile xml "External XML file object";
+        protected
+          Real aux;
         algorithm
-          y := getReal(xml=xml, varName=varName) <> 0;
+          (aux, exist) := getReal(xml=xml, varName=varName);
+          y := aux <> 0;
         annotation(Inline=true);
       end getBoolean;
 
       function getString "Get scalar String value from XML file"
         extends Interfaces.partialGetString;
         input Types.ExternXMLFile xml "External XML file object";
-        external "C" str=ED_getStringFromXML(xml, varName) annotation(
+        external "C" str=ED_getStringFromXML(xml, varName, exist) annotation(
           __iti_dll = "ITI_ED_XMLFile.dll",
           __iti_dllNoExport = true,
           Include = "#include \"ED_XMLFile.h\"",
@@ -598,24 +618,28 @@ package ExternData "Library for data I/O of CSV, INI, JSON, MATLAB MAT, Excel XL
       extends Modelica.Icons.Function;
       input String varName "Key";
       output Real y "Real value";
+      output Boolean exist "= true, if varName exits; = false, if it does not exist and y is set to 0.0";
     end partialGetReal;
 
     partial function partialGetInteger
       extends Modelica.Icons.Function;
       input String varName "Key";
       output Integer y "Integer value";
+      output Boolean exist "= true, if varName exits; = false, if it does not exist and y is set to 0";
     end partialGetInteger;
 
     partial function partialGetBoolean
       extends Modelica.Icons.Function;
       input String varName "Key";
       output Boolean y "Boolean value";
+      output Boolean exist "= true, if varName exits; = false, if it does not exist and y is set to false";
     end partialGetBoolean;
 
     partial function partialGetString
       extends Modelica.Icons.Function;
       input String varName "Key";
       output String str "String value";
+      output Boolean exist "= true, if varName exits; = false, if it does not exist and str is set to a an empty string";
     end partialGetString;
   end Interfaces;