Translation of 4GL names to iSeries

Does anyone have any idea how Lawson determines the iSeries RPG field names when custom tables are created in DBDEF?

We're migrating to LSF9 from 8.1. In 8.1 I created several files under a custom system code. When these files were created, the process came up with the field names. I know that the first character begins with "D", the next three is the file prefix. But how it comes up with the remaining characters, is somewhat of a mystery. I wasn't too worried about it because I wrote my supporting custom programs using the field names that were assigned. However, when migrating to LSF9, I ran into issues with 2 field names. Here is an example of the error I get with one of the fields:
"Sysload Translation INVLNG Already in Use for Element INV-LENGTH"

The field is named DZAYINVLNG in 8.1. Under LSF9 it gets named INV_L00001. It seems to me the translation process has something to do with the element that is chosen for the field name in DBDEF. (that's been my suspicion for awhile). In LSF9, that the process is different. But this is not making sense because we have several custom tables, so why isn't the problem more widespread?