Indirect Address

An indirect address is an absolute, relative, or symbolic address, (or a general register containing an address) of a location that contains another address. An indirect address must be followed by one or more indirection symbols to indicate a corresponding number of levels of indirect addressing.

The indirection symbols are:

The percent sign (%), indicating that the low-order three bytes of the address are used.
The question mark (?), indicating that all 31 bits are used for the address.

To use a general register as an indirect address, specify a decimal integer (0 through 15) followed by an R and a percent sign, or an R and a question mark. For example, if you want to refer to data whose address is located in register 7, you would specify:

7r%

Example: Use of a relative address to form an indirect address.

Address: +A% (One level of indirect addressing)

Example: Comparison of use of % and ?

Address	Data
X	0100A080
0000A080	AAAAAAAA
0100A080	BBBBBBBB

Subcommand	Data Displayed
LIST X	0100A080
LIST X%	AAAAAAAA
LIST X?	BBBBBBBB

Example: Indirect addressing using a combination of indirection symbols.

Address expression: +A%??% (Four levels of indirect addressing)