upd

help.h

@@ -97,6 +97,7 @@ const char *VHELP =\
 "}  monadic behead        all elts of x except first, same as 1_" "\n"\
 "}  dyadic  xor           x ^ y" "\n"\
 "}. monadic curtail       all elts of x except last, same as -1_" "\n"\
+"}. dyadic  band          x & y" "\n"\
 "}: monadic suffixes      suffixes of x, same as }.\\." "\n"\
 "}: dyadic  shr           x >> y" "\n"\
 "[  monadic factors       compute prime factors of x" "\n"\

readme.md

@@ -257,6 +257,7 @@ _: dyadic  base          10_:4242 is 4 2 4 2
 }  monadic behead        all elts of x except first, same as 1_
 }  dyadic  xor           x ^ y
 }. monadic curtail       all elts of x except last, same as -1_
+}. dyadic  band          x & y
 }: monadic suffixes      suffixes of x, same as }.\.
 }: dyadic  shr           x >> y
 [  monadic factors       compute prime factors of x