diff --git a/src/hb-set-private.hh b/src/hb-set-private.hh index bba401517..3c302b1da 100644 --- a/src/hb-set-private.hh +++ b/src/hb-set-private.hh @@ -36,7 +36,15 @@ * "approximate member query". Conceptually these are like Bloom * Filter and Quotient Filter, however, much smaller, faster, and * designed to fit the requirements of our uses for glyph coverage - * queries. As a result, our filters have much higher. + * queries. + * + * Our filters are highly accurate if the lookup covers fairly local + * set of glyphs, but fully flooded and ineffective if coverage is + * all over the place. + * + * The frozen-set can be used instead of a digest, to trade more + * memory for 100% accuracy, but in practice, that doesn't look like + * an attractive trade-off. */ template