> In BSL, for example, [as I learnt it some time ago, at a basic level] the signs for class and group share the hand movement but use respectively the hand-shap

> In BSL, for example, [as I learnt it some time ago, at a basic level] the signs for class and group share the hand movement but use respectively the hand-shapes for C and G; they're compound gestures. Same in ASL. But I wouldn't call it a compound sign, since it's not combining the COLLECTIVE sign with TOPIC CLASSIFIER:INITIAL C/G IN ENGLISH sign. Would you consider ASL HURRY as a compound sign, since it uses the H handshape as a mnemonic in it? How about ELEVATOR and its C? I would consider compound signs to be things like THROAT DOCTOR, PET STORE, SKIRT LONG, where we use two signs with distinct meanings which are easily comprehended in isolation, but when used together communicate a different concept. > One expects to quickly run out of new sounds (or signs) if you don't compound/combine them atomically. I can see this with the limited options available in spoken languages: there only a few hundred ways to combining vowel-consonant pairs, but a few thousand ways to combine fingers+limb+facial expression+short movement (although the challenge becomes how to reduce interpretation errors i.e. was that index finger flicking down 3 times or thumb flicking up twice?).