AT&T 6300 Programmer's Manual page 676

Error Codes
CODE
ID
TM
as
LS
ST
CN
UF
D-6
NUMBER MESSAGE
12 Illegal direct
A statement that is illegal in direct mode is
entered as a direct mode command.
13 Type mismatch
A string variable name is assigned a numeric
value or vice versa; a function that expects
a numeric argument is given a string argu-
ment or vice versa.
14 Out of string space
String variables have caused GWBASIC to
exceed the amount of free memory remain-
ing. GWBASIC will allocate string space
dynamically, until it runs out memory.
15 String too long
An attempt is made to create a string in
excess of 255 characters.
16 String formula too complex
A string expression is too long or too com-
plex to be processed. It should be broken into
smaller expressions.
17 Can't continue
An attempt is made to continue a program
that:
1.
Has halted due to
an
error.
2. Has been modified during a break in
execution.
3.
Does not exist.
18 Undefined user function
A USR function is called before the function
definition (DEF statement) is given.