Well, I don't think there ever was a specific term for that.
What Turbo Pascal calls "typed constants" (which are, in fact, variables, and a non-standard Turbo Pascal extension of the language) are put as one single block into the program executable by the compiler in the exact order the compiler comes across them at compile time.
beaconStr : String  = 'config starts here';
configVar : INTEGER = 1;
"Normal" constants are spread all over the place in the executable by the compiler and are by far not as easy to locate in the binary. Typed constants, however, are collected into one single block at compile time and loaded by the runtimes to the bottom of the data segment.
What you did was, just as shown above, that you put a magic marker (or beacon) at the beginning of the typed constants to be able to find them in the executable, then patched what you found after that. Note this was a bit of a unique feature in Turbo Pascal - other languages and compilers don't necessarily have everything so conveniently put into one place. This "one place" was required because older MSDOS binary formats for COM and .EXE files did not include enough (or rather, any) information on where in the binary the initialized data segment contents is to be found.
I doubt this technique would be reproducible easily with today's operating systems: Program files are typically write-protected for security reasons (which makes the technique much harder today - you need admin privilege to patch an executable), on the other hand, modern object formats actually mark the initialized data segments specifically for the loader, so, constants to patch would actually be easier to find in a documented way, even without a beacon.