Virtual File Name

The Virtual File Name (VFN) is used when transmitting ENGDAT information, to link together the multiple files that may make up the ENGDAT folder. The structure of the 26-character VFN is shown below:

• Characters 1 to 3 - The text 'ENG', to identify this file as a member of an ENGDAT folder
• Characters 4 to 20 - Exchange reference number of the folder
• Characters 21 to 23 - Total number of files within the folder (including the ENGDAT header)
• Characters 24 to 26 - Sequence number of this file within the folder (the ENGDAT header is always sequence number 1)

Example of virtual filename structure

This is an example of three CAD-files; two in neutral format and one in native format.

The ENGDAT message describes how to manage these CAD-files and the content of the files. The exchange reference number in this case is 98316.

Note that the zeroes before the exchange reference keep the positioning within the filename correct. The same rule applies to the handling of {No. files} and {File No.}.

ENG{Exchange ref}{No. files}{File No.}

ENG00000000000098316004001 (ENGDAT message)

ENG00000000000098316004002 (VDAFS-file)

ENG00000000000098316004003 (SET-file)

ENG00000000000098316004004 (NATIVE-file)