Thank-you for your recent request. I appreciate your concern as to the definition of income in the Internal Revenue Code. I am a Communication Expert and have made an extensive study of the morpho-syntax of English. I have a Master's Degree from the University of Colorado in Communications and I have over fourteen years of experience teaching English and Communications at the elementary, junior-high, high school, and college levels. Source is not to be equated with income as these terms are used in the above citation.
Participles are verbal adjectives which modify nouns.
The restrictive phrase appears following the noun it modifies without commas. A restrictive phrase is an inextricable part of the sentence because there are no commas. The non- restrictive phrase can be eliminated with out changing the basic sentence. That is the purpose of setting it apart with commas. Adjectives always modify the noun immediately preceding when the word or phrase is placed with intervening commas.