In the Interbase Operations Guide
I found that

"Maximum row size is 64Kb.
Each Blob and array contributes eight bytes to this limit in
the form of their Blob handle.
Systems tables (tables maintained by the InterBase engine for system
data)
have a row size limit of 128Kb."

The definition of "row" in a database is unambiguous.
Is one row the same as one Tuple?

Regards

Matt