Statements
The assembler language has three kinds of statements: instruction
statements, pseudo-operation statements, and null statements. The
assembler also uses separator characters, labels, mnemonics, operands,
and comments.
Instruction statements and pseudo-operation statements
A instruction or pseudo-op statement has a predefined syntax.
Null statements
The null statements are useful primarily for making assembler source code easier for people to read.
Separator characters
The separator characters are spaces, tabs, and commas.
Labels
The label entry is optional. The assembler gives the label the value contained in the assembler’s current location counter.
Mnemonics
The mnemonic field identifies whether a statement is an instruction statement or a pseudo-op statement.
Operands
The existence and meaning of the operands depends on the mnemonic used.
Comments
The comments option is optional in assembler.