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Global File Structure


The M capabilities of string-valued array subscripting offer a simple, general way to cross-reference VA FileMan files. To minimize the number of global names used by the system, FileMan stores each cross-reference set as a descendent of an alphanumeric subscript of the file's global. A file, such as an EMPLOYEE file, that should be accessible by name, is set up by the system so that there is a subscript "B", which in turn is subscripted by strings corresponding to the first 30 characters from the .01 field for every entry in the file. For each such string-valued subscript, the next level of subscripting contains the internal entry numbers of the entries that contain the name.

Let's add to our previous example a second employee, internal entry number 9, also named John Jones, and a third employee, internal number 7, whose name is Sam Smith. Then you would have:


Notice that all the data is in the subscripting and the global nodes under ^EMP("B") are simply null strings. FileMan allows for these strings to be non-null in the case where a mnemonic cross-reference is set up for the name. Multiple cross-references (C, D, etc.) are also allowed.

In Version 22.0 of VA FileMan, cross-references (indexes) may be defined that have more than one data field subscript before the record number. These cross-references can then be used for a lookup and the user will be prompted for more than one lookup value, one for each data subscript on the index. Such compound indexes must be defined as a new-style index on the INDEX fileNew/Updated with VA FileMan V. 22.0

Example: An entry from a cross-reference with the name and the date-of-birth on the data above might look like:



Reviewed/Updated: March 10, 2007