What is a macro instruction?

The macro facility

presented thus far capable of inserting blocks of instruction in

place of macro calls. All of the calls to any given macro will be

replaced by identical blocks. This macro facility lacks

flexibility: there is no way for a specific macro call to modify

the coding that replaces it. An important extension of this

facility consists of providing for arguments, or parameters, in

macro calls.

Corresponding

macro dummy arguments will appear in macro definitions.

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"margin-bottom:.0001pt;line-height:normal;">A 1, DATA 1

"margin-bottom:.0001pt;line-height:normal;">A 2, DATA 2

"margin-bottom:.0001pt;line-height:normal;">A 3, DATA 3

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"margin-bottom:.0001pt;line-height:normal;">A 1, DATA 2

"margin-bottom:.0001pt;line-height:normal;">A 2, DATA 2

"margin-bottom:.0001pt;line-height:normal;">A 3, DATA 2

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"margin-bottom:.0001pt;line-height:normal;">DATA 1 DC F '5'

"margin-bottom:.0001pt;line-height:normal;">DATA 1 DC F '10'

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"margin-bottom:.0001pt;line-height:normal;">In this case the

sequence are very similar but not identical. The first sequence

performs an operation using DATA1 as operand; the second perform

using DATA2. They can be considered to perform the same operation

with a variable parameter or argument. Such a parameter is called a

macro instruction argument, or dummy argument. It specified on the

macro name line and distinguish by the ampersand which always its

first character