## Presentation Device Driver Reference for OS/2

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### File Version Field Checking

Executable files can be tagged with a file version string in the description field of their executable file header. This field can be set during program linking. The format of a file version string is as follows:

    <header> <version string> <trailer>

where:

<header> is a two-character string: @#.

<version string> is twelve characters defined as xxx:YYYYYYYY, where xxx is used to identify the vendor that created the file (for example, IBM) and YYYYYYYY is a file version number (for example, 0006.307). This file version number can be interpreted as a floating point number or as an integer.

<trailer> is the two-character string: #@.

An example of a file version string would be:

@#IBM:0006.307#@.

If both the source and target versions of a file contain file version strings, the file version checking is performed. For a file version check to be considered successful, the vendor identifiers of the source and target files must match and the file version number of the source file must be greater than or equal to the file version number of the target file. If the file version check succeeds, then the source file is copied over the target file. If not, DSPINSTL prompts the user to decide whether to replace the target file. If the source file contains a file version field, but the target file does not, then the source file is assumed to be more recent than the target file and is copied over the target file.