From the API docs, Transaction chapter:

isc_tpb_read Read-only access mode that allows a transaction only to select
data from
Tables

What is the exact significance of this? Does it just stop me from performing
updates and throw an exception? Or if I am only doing reads, does it have
performance or memory benefits? Ie are there reasons to specify isc_tpb_read
instead of isc_tpb_write?