(?<![a-zA-Z]) emulates \b at the beginning of an alphabetic string and (?![a-zA-Z]) emulates \b at the end of an alphabetic string.

But as I explained before, it doesn't seem from iaw4's problem description that asserting a boundary match is even needed.

UPDATE: Removed color.

In reply to Re^5: Defining Characters in Word Boundary? by Jim
in thread Defining Characters in Word Boundary? by iaw4

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