Just goes to show that there is always something new to learn, I've never knowingly encountered this form before, but there it is documented. Albiet that it seems to be a non-feature as they are still not callable in the normal way. But, I sit corrected :)

Five specially named code blocks are executed at the beginning and at the end of a running Perl program. These are the BEGIN, UNITCHECK, CHECK, INIT, and END blocks.

These code blocks can be prefixed with sub to give the appearance of a subroutine (although this is not considered good style). One should note that these code blocks don't really exist as named subroutines (despite their appearance).