Mary... You cannot access an attachment file the same way you do with database files. These are special attachment files attached to the primary table being updated, in this case; PAGRDI. When this table was created it was flagged as being able to support "attachments" in the dbdef. There is an entire set of API's that are used to access these files. The documentation of attachment files is as such... Attachments Specifies whether attachments, such as Comments, are allowed with this file. Comments are useful for linking narrative text to specific data.
Yes creates two attachment files that are related to the attachment-enabled data file and are named as follows:
L_HPrefix
L_DPrefix
where Prefix is the prefix of the data file to which the attachments are related; L_H indicates a header attachment file (the first 512 bytes of the attachment), and L_D indicates the detail attachment file (the remaining bytes, up to 32,000, of the attachment).