Is there a way to have a summary field that bases its value off of *all* records in a table, not just the found set of records? Or some other way to accomplish this task, as part of a field definition?

Specifically, I'm wanting to create a "count of" that counts all the records for which a certain other field has a particular value (well, any value really), but have it based on all the records in the whole table, not just the found set. Because I will be viewing it through a portal inside a related table, the found set only consists of the related records, but I want it to calculate it based on all records.

It used to work back in FMP 4 or 5, however it no longer worked as of v6; perhaps FMP used to base summary fields off of all records in a database, or maybe it used to not automatically make the found set just the related records when viewing through a portal. Either way, I haven't been able to figure out either a summary or calculation to do this. Any suggestions would be much appreciated!

The Cartesian join, signified by the X in the relationship definition, allows one table to be related to all records in another table or itself, similar to the way a constant calculation of 1 was used for previous versions. So, create a relationship using this join and then use Count( rel::field ).

There has been no change in FM4 to FM6 for summary fields. Summary fields have always been based on the found set. Your terminology is unclear. You say you want a count of all records, and then you say you do NOT want a count of all records. You appear to want a count of related records where the relationship is a self-match on a particular field.