Do you really want username or AccountName? Account Name is what is used with a password for accessing your database and username is a setting in filemaker preferences.
What exactly do you mean by "choose certain files"?
Files stored in container fields? or ???
first of all thank you so much for your quick response. We are a small firm with approximately 10 users logging into a FileMaker server. The actual script is basically just a find request in certain fields to view in-house messages in the "messages" database that are directed to the individual. Each of the 10 computers has its own "username" so that if you were to use a script to "enter username" it pasted initials. We are concerned that one individual is opening up scripts in messages to see those found messages for a different individual. So what I want to do is start off the script that does a particular finding with some kind of an inquiry as to whether or not this particular "username" machine is being used to activate the script and if so simply send them a note that they are not authorized to review this information. I hope this is a sufficient enough explanation and again I truly thank you for your help.
But it's easy for your user to use a different user name and either gain access to the wrong records or to be denied all access. It's much better to define accounts and passwords and use the account name to control access to specific records.
Once users have individual accounts and passwords, you can use record level access control to limit who can access indivdual records in your tables.
See "Editing record access privileges" in FileMaker Help and check out this particular sub section: "Entering a formula for limiting access on a record-by-record basis" for a description of how to set this up.