Partial Data Fields

Hullo,

I have tried searching with google and havent had much luck.

Autocad has the ability similar to Excel to have a custom data field (eg. modifying a date data field from 05/28/1988 to 28/05/88 just by changing variables.

I would like to be able to have a data field that automatically uses the file name as the drawing number - but with out the guff at the end of the file name  (eg. 1900-SS-S-0001 Control Plan R01 becomes within the paper space drawing number field 1900-SS-S-0001 )

I would also like to add a Revision Field that looks at the end of the file name.

Any help even if it is - "It cant be done" is appreciated. 

I am not the best user of the forums. 

Thanks

John