address for resolving branches back to this point during execution,
and then a 0 as a marker so as to allow for an unknown number of block
exit points.
+
+====
+.Usage example {counter:example}:
+----
+: WTELL ( tfa -- ; Print word pname )
+ 24 + DUP 8 + SWAP @ TELL SP EMIT
+;
+
+: WORDS ( wordlist -- ; Print all words of word list )
+ BEGIN
+ @ DUP 0= IFBREAK
+ DUP WTELL
+ END
+ DROP
+ NL EMIT
+;
+----
+====