I have researched this site thorougly for information on multi-key techniques and have seen several posts, but nothing to explain it. Please forgive a beginner. FM help says it's simply a many-to-many. That doesn't appear to be what the forum posts were referring to. What I envisioned was a method of writing more than one Key field (for instance Invoice#) within one field (Service:Invoice#) that allowed each Invoice# to be listed and it's related child looked up. I hope I'm making sense. Seems I remember something about doing this using carriage return. I think I want something similar to Colbat Sky's Rolling Log, EXCEPT, I don't want it to write to individual records but to individual lines within a fields record. From what I've heard, I DON'T want to consider Repeating fields. This (I believe) would need to be held within a text (or numberic) field and not left within a global.

Can someone clarify ?

No, not multiple key *fields*.... mutliple values in the *one* key field separated by carriage returns.

Thusly: the following values entered into a prinary key field...

1

Yes, a multi-key field is simply a key field (defined as a text field) with more tha one line in it. The carriage return stops indexing on one value and starts indexing on the next, so that as Vaughan says, separate groups of related records can be addressed from the one key field.

To write to a key field, you would normally use:

Set Field ["YourKeyField", "DesiredKeyValue"]

but to write to a multi-key field, you would use something along the lines of:

Set Field ["YourKeyField", "Case(not IsEmpty(YourKeyField), "

I might be confusing myself again ... that happens more and more as I get older but, if the multi-key is TEXT and the LineItems:Invoice# is numeric won't I have a mis-match data type?

I think I just answered my own question. I will be joining on the unique s/n discussed, right Ray? AND, that will also be a text field.

Yes, that's right - both fields will be text.