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Common Syntax Errors 235
Common Syntax
Errors
When you press the Escape key to exit from the Administration Console’s
built-in editor or when you load a packet filter definition from across the
network, the software examines the definition for syntax errors. Table 34
lists syntax errors and their causes.
Table 34 Common Syntax Errors
Syntax Error Description
Opcode not found
OR
Unknown opcode
An opcode was expected on the line and was not found.
The opcode must be one of those described in “Packet
Filter Opcodes” later in this chapter and must include the
size, if any. The opcode and size must be separated by a
single period (.) with no intervening spaces. Any mix of
uppercase and lowercase characters is permitted.
Operands are not the
same size The opcode requires two operands of the same size. The
top two operands on the stack are of different sizes.
Stack underflow The opcode requires one or more operands. An insufficient
number of operands are currently on the stack.
Stack overflow The opcode pushes an operand on the stack. The stack
does not have sufficient room for the operand.
No result found on top
of stack The program must end with a byte operand on the top of
the stack. After the last instruction in the program is
executed, the stack is either empty or contains an operand
other than a byte.
Extra characters on
line The source line contains extraneous characters that are not
part of the instruction and are not preceded by a comment
character (#).
Expected a byte
operand The opcode requires a byte operand as one of its
parameters. The operand is of a size other than a byte.
Offset not found The opcode requires an offset to be specified. None was
found on the line.
Literal not found The opcode requires a literal value to be specified. None
was found on the line.
String not found The opcode requires a quoted string to be specified. None
was found on the line.