#once #create message .ND .tr %$ .EQ delim $$ .EN .LP It is also quite permissible to leave out either the "from" part or the "to" part of a from-to construction. For example, modify "Example" so its output looks like this, then type "ready". .pl 1 #once #create Ref .LP .EQ lim from {x-> pi /2} ( tan~x) sup {sin~2x}~=~1 .EN .pl 1 #once #create Example .LP .EQ lim from xxx ( tan~x) sup {sin~2x}~=~1 .EN .pl 1 # #once neqn Ref | nroff >X1 & #once neqn message Ref | nroff -T$term %s/tinyms - #user neqn Example | nroff >X2 #cmp X1 X2 #log #next 7.1d 10 7.2c 5