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PDGREPPE Pattern Standards

PDGREPPE follows some standards in its pattern specification.

This helps PDGREPPE and You to relate use of PDGREPPE to other
valuable Search and Replace tools and technology.

Some parallel Standards that PDGREPPE MAGIC tracks are:

POSIX

Various matching symbols and forms used by PDGREPPE are part of
the POSIX standard in IEEE group 1003.2.

POSIX is an abbreviation for the Portable Open System in Unix.

"POSIX.2" or "1003.2" is the IEEE group that has defined the
symbols and forms that should exist in UNIX command line
utilities to include Regular Expressions (RE's).

Section 2.8 in POSIX standard 1003.2 specifically addresses
RE's.

Many of the pattern symbols that occur in ERE used by PDGREPPE
are found in the POSIX standard.

Some of these are:

	.	Any
	[set]	Character Class
	+	One or More Repetitions
	?	One or Zero Repetitions
	*	Zero or More Repetitions
	{j,k}	Repetitions Boundaries
	<	Start of Word
	>	End of Word
	^	Start of Line
	$	End of Line
	|	OR
	(grp)	Marked Group

Symbols and "forms" like these are also found in "magic" pattern
searches conducted by applications like the Microsoft word
processor MS-WORD in its Search and Change dialogs that use a
"Wild Cards" option.

GNU

PDGREPPE uses some of the SAME option letters that some other
GREP's use such as "-b", "-A<d>", "-P<d>" and "-e<d>" used by
GNU Grep.

Also, the replacement symbols in the ERE of PDGREPPE are similar
to those in GNU Emacs.

ZYLABS

Pattern Definition Language (PDL) uses the same symbol "@" for
identifying Definitions in Search/Replace patterns as other
definition interpreters from companies like ZYLABS and their
product line that includes the ZYINDEX compiled-index location
applications and libraries.

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