Refers to the (unfortunately very-seldom-practiced!) consideration of using a separate hand-held rubber eraser --- or at least to slip on one of those much-longer-lasting wedge-shaped "supplementary" eraser-caps if you know you'll be doing a lot or error-expunging --- to clean most of your mistakes instead of just mindlessly consuming your
pencil's minuscule built-in eraser, so that you
don't wear da entire
0%!$&#@ eraser clear down to the
metal ferrule before the
pencil's even been "sharpened away" much at all, causing any unfortunate
person who subsequently attempts to use said
pencil to not have any eraser left for "emergency" erasures (i.e., where he needs to make a quick correction in a tense/flurried situation, like trying to hastily jot down a phone number or address, or to quickly fill out a form where neatness is a must). It helps eliminate waste, as well --- think how many still-perfectly-usable pencils (i.e., they still have most of their "length" remaining) likely
get discarded just because their erasers are worn down.
I always bring along a few
pencil cap erasers in my purse, since I know how few people actually practice
pencil-eraser etiquette, and so oftentimes the only pencils that will be lying around for people to use will not have any eraser left.
P.S. There's also such a thing as "pencil-POINT etiquette --- if ya wear down the lead in a "public" pencil, such as a string-tethered one for a "customer comments" notes-
box, practice a little fellow-
human consideration by scraping away a bit of the wood at the tip to expose a little of the graphite
core again (here's where always carrying a small pen-knife --- or even better, one of those tiny two-finger-grip "
dog-bone" or "hourglass" style sharpeners --- can come in handy), so that da next patron who wishes to fill out a store-satisfaction card can have enough of a point on da pencil to actually do so!