The following keywords are built into Blitz, and may not be used as identifiers (variables, function names, labels, etc.):
{% code overflow="wrap" %}
After, And, Before, Case, Const, Data, Default, Delete, Dim, Each, Else, ElseIf, End, EndIf, Exit, False, Field, First, Float, For, Forever, Function, Global, Gosub, Goto, If, Insert, Int, Last, Local, Mod, New, Next, Not, Null, Or, Pi, Read, Repeat, Restore, Return, Sar, Select, Shl, Shr, Step, Str, Then, To, True, Type, Until, Wend, While, Xor, Include{% endcode %}