TESU 90 credit 1 source limit

[a_dblu]

When TESU says you can only transfer 90 credits from one source, how do they define one source?

Is ACE credit 1 source (i.e. Saylor, Straighterline, etc. are all ACE credit hence 1 source)?

OR

Do they count each content provider separately, even though the credit may all come from ACE? (i.e. Saylor, Straighterline, etc are each 1 source, even though they all provide ACE credit.)

Thanks in Advance!