Data attributes

The data, such as instructions, constants, and areas, that you define in a source module, can be described by its:

Type, which distinguishes a property of a named object or macro argument, for example, fixed-point constants from floating-point constants, or machine instructions from macro instructions
Length, which gives the number of bytes occupied by the object code of the named data
Scaling, which shows the number of positions occupied by the fractional portion of named fixed-point, floating-point, and decimal constants in their object code form
Integer, which shows the number of positions occupied by the integer portion of named fixed-point and decimal constants in their object code form
Count, which gives the number of characters that are required to represent the named data, such as a macro instruction operand, as a character string
Number, which gives the number of sublist entries in a macro instruction operand
Defined, which determines whether a symbol has been defined prior to the point where the attribute reference is coded
Operation Code, which shows if an operation code, such as a macro definition or machine instruction, is defined prior to the point where the attribute reference is coded

These characteristics are called the attributes of the symbols naming the data. The assembler assigns attribute values to the ordinary symbols and variable symbols that represent the data.

Specifying attributes in conditional assembly instructions allows you to control conditional assembly logic, which, in turn, can control the sequence and contents of the statements generated from model statements. The specific purpose for which you use an attribute depends on the kind of attribute being considered. Here are the attributes and their main uses:

Table 1. Data attributes
Attribute	Purpose	Main Uses
Type	Gives a letter that identifies type of data represented	In tests to distinguish between different data types For value substitution In macros to discover missing operands
Length	Gives number of bytes that data occupies in storage	For substitution into length fields For computation of storage requirements
Scaling	Refers to the position of the decimal point in fixed-point, floating-point, and decimal constants	For testing and regulating the position of decimal points For substitution into a scale modifier
Integer	Is a function of the length and scale attributes of decimal, fixed-point, and floating-point constants	To keep track of significant digits (integers)
Count	Gives the number of characters required to represent data	For scanning and decomposing character strings As indexes in substring notation
Number¹	Gives the number of sublist entries in a macro instruction operand sublist, or the maximum subscript of a dimensioned SET symbol to which a value has been assigned.	For scanning sublists As a counter to test for end of sublist For testing array limits
Defined	Shows whether the symbol referenced has been defined prior to the attribute reference	To avoid defining a symbol again if the symbol referenced has been previously defined
Operation Code	Shows whether a given operation code has been defined prior to the attribute reference	To avoid assembling a macro or instruction if it does not exist.
Notes: The number attribute of &SYSLIST(n) and &SYSLIST(n,m) is described in &SYSLIST System Variable Symbol.

Attribute reference

attribute_notation': Is the attribute whose value you want, followed by a apostrophe. Valid attribute letters are D, O, N, S, K, I, L, and T.
ordinary_symbol: Is an ordinary symbol that represents the data that possesses the attribute. An ordinary symbol cannot be specified with the operation code attribute.
variable_symbol: Is a variable symbol that represents the data that possesses the attribute.
literal: Is a literal that represents the data that possesses the attribute. A literal cannot be specified with the operation code attribute or count attribute.
character_string: Is a character string that represents the operation code in the operation code attribute.

Examples:

T'SYMBOL
L'&VAR
K'&PARAM
O'MVC
S'=P'975.32'

The assembler substitutes the value of the attribute for the attribute reference.

Reference to the count (K'), defined (D') and number (N') attributes can be used only in conditional assembly instructions or within macro definitions. The length (L'), integer (I'), operation code (O'), type (T') and scale (S') attribute references can be in conditional assembly instructions, machine instructions, assembler instructions, and the operands of macro instructions.