The operand field follows the mnemonic field and contains zero or more comma-separated operands. An operand can be one of the following:
An immediate operand is encoded directly in the instruction. The value of an immediate operand must be a constant expression. Most instructions with an immediate operand require an absolute constant expression, such as 1234. Some instructions (such as a call instruction) allow a relocatable constant expression, such as a symbol defined in another file. (See Section 4.9 for details about types of expressions.)
A register operand is a special pre-defined symbol that represents a CPU register.
A memory reference operand uses one of several memory addressing modes to refer to a location in memory. Memory reference operands use a special target-specific syntax defined in the appropriate CPU and Instruction Set Reference Guide.
You must separate operands with commas. Not all operand types are supported for all operands. See the description of the specific instruction in the CPU and Instruction Set Reference Guide for your device family.