In Glicol a `~name` bus is silent until another chain references it

A chain whose name starts with ~ is a bus: it produces no sound on its own and is only heard when another chain references it (mix ~name, mul ~name, lpf ~name 1.0, …). This is the mechanism that lets you build voices without them all reaching the speakers. The flip side is a common bug: forgetting the leading ~ turns an intended bus into an extra master output that plays directly. Referencing a bus name that doesn’t exist (e.g. a typo ~t1 for ~t) raises a NonExistReference error.

Examples

~lead: saw 220 >> lpf 800 1.0 // silent alone out: mix ~lead >> mul 0.4 // now audible lead: saw 220 ... // missing ~ → plays straight to speakers

Assessment

A performer defines ~pad: ... but hears nothing. Give two distinct explanations (one about referencing, one about the ~) and how to test each.