This directory (i.e., src/modules/plain) contains a collection of "primary"
single-file extension modules for MonetDB.

Here, "primary" refers to the fact that these modules are considered "vital"
for MonetDB, and hence, they are supposed to be officially supported.
Seven of these modules (i.e., algebra, arith, bat, builtin, str, sys, trans)
are "mandatory" and by default loaded when Mserver is started.
