STEM provides a mechanism to retrieve data from other sources besides the current model; specifically inputs or results from other STEM models, Microsoft Excelspreadsheets or workbooks (up to and including Excel 2000) and any databases which support the Open Database Connectivity (ODBC) standard. An
external reference
is a string of text used in a formula to identify the required data.
The form of an external reference is '<filename>'!<reference>. The <filename> is enclosed in single quotes to prevent special characters being mis-interpreted as another part of a formula. The format of the <reference> depends on the type of external file.
For an input from another STEM model, the <reference> is just an internal reference, as described above. For an Excel file, it may be a cell reference (e.g.,
R1C2
or $A$2), or a name which is defined in the worksheet.
Note: If an Excel workbook contains several sheets, the name of the sheet must also be specified, as in the following example:
'C:\DATA\[COSTS.XLS]Sheet3'!$A$2
This is the same format as is used in Excel for an inter-workbook link.
For a database, the <reference> will be interpreted as the name of a database table or query, or as an explicit Structured Query Language (SQL) query.