details on record Format Level Identifier

Anyone know how a file's record Format Level Identifier is formed? (NOTE
that I am not asking about the File Level Identifier, which is a timestamp
of the object's creation.)

Maybe the better question is ask if there's a way to quickly determine
whether two physical files share the same layout, in this case, defined as
same fields, field attributes, position in format, etc.? THE ONLY
DIFFERENCES being the filename and record format name.

Here are the Format Level Identifiers from three physical files that are
identical in definition except for the filename and format name:
4A3ECDFF3B3AD
4A3ECDFF3A6B8
4A3ECDFF3A6A9

The identifiers are identical except for the last 4 characters. So, being
the inquisitive type, I wonder if I can make a judgement on the first 9
characters matching to mean that they use the same layout. I'm not sure
testing will bear this out, and InfoCenter doesn't get specific on this
point.

Anyone know? Or know of specific RTF links?

TIA, Dan