A macro definition must begin with a %MACRO statement and must end with a %MEND statement. The macro definition can include macro language statements as well as SAS language statements. When the macro is compiled, macro language statements are checked for syntax errors. The compiled macro is stored in a temporary SAS catalog by default.

To include positional parameters in a macro definition, you list the parameters in parentheses and separate them with commas. When the macro is executed, macro variables will be created in the local symbol table and will have the same names as the parameters. You can then use these macro variables within the macro.

To call a macro that includes positional parameters, you precede the macro name with a percent sign. You list the values for the macro variables that are defined by the parameters in parentheses. List values in the same order in which the parameters are listed, and separate them with commas. Remember that a macro call is not a SAS language statement and does not require a semicolon.

In a mixed parameter list, positional parameters must be listed before any keyword parameters. Both positional and keyword parameters create macro variables in the local symbol table. To assign a null value to a keyword parameter, you list the parameter without a value in the macro call.

When you submit a macro definition, the macro is compiled and is stored in a SAS catalog. Then when you call the macro, the macro is executed. The macro is available for execution anytime throughout the current SAS session.

You can use %IF-%THEN statements to conditionally process code. Within a %IF-%THEN statement, you must use %DO and %END statements to enclose multiple statements. %IF-%THEN statements are similar to IF THEN statements in the DATA step, but they are part of the macro language.

By using %IF-%THEN statements, you can place whole steps, individual statements, or parts of statements onto the input stack.

There are several ways to create macro variables in the local symbol table. Macro variables that are created by parameters in a macro definition or by a %LOCAL statement are always created in the local table. Macro variables that are created by a %LET statement or by the SYMPUT routine inside a macro definition might be created in the local table as well.

To define macros with %DO loops you use a %DO statement and a %END statement. Be sure to precede all keywords in the statements with percent signs since the %DO and %END statements are macro language statements. Also, be sure to end these statements with semicolons.

When you submit a call to a compiled macro, the macro is executed. Specifically, the macro processor executes compiled macro language statements first. When any SAS language statements are encountered, the macro processor places these statements onto the input stack and pauses while they are passed to the compiler and then executed. Then the macro processor continues to repeat these steps until the %MEND statement is reached.