Index: class.doc
==================================================================
--- class.doc
+++ class.doc
@@ -41,10 +41,11 @@
   '  Key code
   :  Label
   %  Local variable
   #  User message
   !  User sound
+  &  User function
 
 Comments are also allowed; these start with a semicolon (outside of a
 string literal) and end at the next line break.
 
 
@@ -220,16 +221,23 @@
 
 (@<name> Array <rows> <columns>)
   Define a global variable whose value is a reference to a new array, with
   the specified dimensions. The maximum number of rows is 64, and the
   maximum number of columns is 1024, and the maximum number of cells in
-  all arrays in total is 65534.
+  all arrays in total is 65534. All elements are initialized to zero when
+  the level starts.
 
 (<message> <code...>)
   Defines a default message code for all classes which do not specify
   their own code for this message.
 
+(&<name> <code...>)
+  Define a user-defined function. User-defined functions may take any
+  number of inputs from the stack and leave any number of outputs on the
+  stack, but may not access user-defined local variables. (It may still
+  access standard local variables, and all global variables, though.)
+
 
 === Class definitions ===
 
 Within a class definition, the following definitions can be used. See also
 the section about variables; many of these definitions are used to specify
@@ -909,10 +917,24 @@
 
 Many instructions are state-changing instructions; these instructions are
 marked with ** in the summary line. Such instructions are not allowed to be
 used on the same turn as the IgnoreKey instruction.
 
+<label>
+  Define a label. Labels are local to the current class. (Label names
+  always start with a colon.)
+
+=<label>
+  Go to a label. (Put the colon after the equal sign; this instruction,
+  and the one below, are using a double sigil.)
+
+,<label>
+  Call a label as a subroutine; when it returns, comes back to here.
+
+<function>
+  Call a user-defined function.
+
 .  ( x -- )
 
 +  ( in1 in2 -- out )
   Add two numbers together.
 

Index: exec.c
==================================================================
--- exec.c
+++ exec.c
@@ -1442,10 +1442,11 @@
     case OP_FLUSHCLASS: NoIgnore(); StackReq(1,0); t1=Pop(); if(t1.t==TY_CLASS) flush_class(t1.u); else if(t1.t==TY_NUMBER && t1.s==-1) flush_all(); else if(t1.t) Throw("Type mismatch"); break;
     case OP_FLUSHOBJ: NoIgnore(); flush_object(obj); break;
     case OP_FLUSHOBJ_C: NoIgnore(); StackReq(1,0); i=v_object(Pop()); if(i!=VOIDLINK) flush_object(i); break;
     case OP_FOR: NoIgnore(); StackReq(3,1); t3=Pop(); t2=Pop(); t1=Pop(); ptr=v_for(code,ptr,t1,t2,t3); break;
     case OP_FROM: StackReq(0,1); Push(OVALUE(msgvars.from)); break;
+    case OP_FUNCTION: execute_program(classes[0]->codes,functions[code[ptr++]],obj); break;
     case OP_GE: StackReq(2,1); t2=Pop(); t1=Pop(); Push(NVALUE(v_unsigned_greater(t2,t1)?0:1)); break;
     case OP_GE_C: StackReq(2,1); t2=Pop(); t1=Pop(); Push(NVALUE(v_signed_greater(t2,t1)?0:1)); break;
     case OP_GETARRAY: StackReq(3,1); t3=Pop(); Numeric(t3); t2=Pop(); Numeric(t2); t1=Pop(); Push(v_get_array(t1,t2.u,t3.u)); break;
     case OP_GETINVENTORY: StackReq(2,2); t2=Pop(); t1=Pop(); v_get_inventory(t1,t2); break;
     case OP_GOTO: ptr=code[ptr]; break;