Parsing Variable Length Delimited Records

I am running SQLServer 2000 to parse and store records in the EDIX12
format. This consists of variable length delimited records which
I am passing to the "transforms" tab to process with VBScript.



The problem is though each segment has a defined number of fields, N,
the standard states that if the final M fieds are empty/blank they are
not to be sent. Thus, a segment defined to have 20 fields may
have 6 the first time I see it, 13 the next time, etc. To access
the columns in VBScript I use DTSSource("Col001"). This works as
long as the columns are there, but gives an error when they are
not. Is there a parameter telling me how many columns are
defined? Or is there something akin to IFEXISTS("Colxxx") or
exceptions?



How can I handle this situation? One suggestion has been to pass
the entire segment to the Transforms section and break it up there.



Finally, what resources can yuo point me to for reference? I'd
like to get good at using DTS since my client wants their project
written for it.



Thanks for yuor help,

--greg