1. Independent reports: One statement is cited while the other is omitted, with no change to its meaning: abbreviation may be permissible.
2. Essential qualification omitted: A condition or exception disappears and changes the claim: the abbreviation is not faithful.
3. Clear indication of an omission: The retained wording strongly points to the missing qualification: further contextual examination may justify a shortened rendering.
4. Unknown relationship: A narrator cannot determine whether the deleted portion controls the rest: unexamined deletion is unsafe.
The principle is not to quote fewer words for its own sake, but to preserve the meaning correctly. Reproducing only original words does not rescue an abbreviation that has become misleading.