TIRFNUM and TIRFCHR represent toolset functions Numtext and Textnum respectively.
The main Gen 8.6 techdocs reference pages for the 2 functions are shown below:
TIRFNUM - Numtext:
Gen™ 8.6 > Developing > Designing > Using Toolset > ... > Functions in Action Diagram > Numtext
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Numtext obtains the integer numeric representation of a character string. Input is a character string or character view. The only special characters allowed in the input string are plus (+), minus (-), and period (.). Output is an integer; it does not contain either sign or the period as a decimal.
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TIRFCHR - Textnum:
Gen™ 8.6 > Developing > Designing > Using Toolset > ... > Functions in Action Diagram > Textnum
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Textnum converts the integer portion of a number value in a number-domain attribute into a text value in a text-domain attribute. Input is a number or numeric view. Output is a character string that contains only the integer value. ...
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Searching the Gen 8.6 techdocs using strings Numtext and Textnum will also find other references.