Deon wrote (2020-07-03):

 ML>> JAM does not have the limitations that squish has... it has its own
 ML>> limitations but they allow for larger areas than most other message
 ML>> base formats...

 DG> What are the Jam limitations? (Just preparing for what I might be in
 DG> for...)

https://defsol.com/news/jammbp-the-joaquim-andrew-mats-message-base-proposal/

Jam also uses 32 bit for the "offset of text in ????????.JDT file". A JAM base
can store more messages than a Squish base as the *.jdt file only includes the
text (message body) and not the header, kludge lines and SEEN-BYs. The file
size is still limited to 4 GB.

JAM's uint32 unix time overflows in 2106-02-07, Squish can store dates up to
2107-12-31 (dos time).

Overall there are not that much different.

Advantages of Squish:
It can store a message exactly as received
All essential data is stored in in the *.sqd file in one piece. Easier to
repair.
Unique message IDs

Advantages of JAM:
No message linking limits
Full 5D (if FTNs would support it)
Has better support for non-FTN messages (in theory)

---