The third edition of Garner’s Modern American Usage reflects several new practices. Invariably inferior forms, for example, are now marked with asterisks preceding the term or phrase, a marking common in linguistics.
The most interesting new feature is the Language-Change Index. Its purpose is to measure how widely accepted various linguistic innovations have become. Such a measuring system for usage guides was first proposed by Louis G. Heller and James Macris in 1967. They noted that “usage specialists can make a clear-cut demarcation of phases in the evolutionary process relevant to the inception and development of alternative terms.”
In these tips, the five stages are tagged as:
Stage 1 (“rejected”): A new form emerges as an innovation (or a dialectal form persists) among a small minority of the language community, perhaps displacing a traditional usage (e.g.: “your” misused for “you’re”).
Stage 2 (“widely shunned”): The form spreads to a significant fraction of the language community but remains unacceptable in standard usage (e.g.: *”pour over books” for “pore over books”).
Stage 3 (“widespread but . . .”): The form becomes commonplace even among many well-educated people but is still avoided in careful usage (e.g.: “clinch” misused for “clench”).
Stage 4 (“ubiquitous but . . .”): The form becomes virtually universal but is opposed on cogent grounds by a few linguistic stalwarts (die-hard snoots) (e.g.: “often” pronounced “OF-tuhn”").
Stage 5 (“fully accepted”): The form is universally accepted (not counting pseudo-snoot eccentrics) (e.g.: “decimate” for inflicting large-scale destruction).