Does a predefined abbreviation imply the meaning of another undefined (but fundamentally similar) abbreviation?

I've defined abbreviation UDES representing untimed discrete-event systems. Now, I need to talk about the larger class of discrete-event systems, which includes the former one.

I'm wondering whether I can directly use DES abbreviation (because I've already defined UDES) or I have to first define DES as discrete-event systems then using its abbreviated form (because it's an independent concept whose abbreviation must be firstly defined).

Answer

As a reader, I'd personally find it confusing if DES were not defined in its own right, although I'll grant that this could depend on context. If readers are likely to already be familiar with DES as an acronym for discrete-event systems, then it might be appropriate to omit the definition where space is limited.

If DES is likely to be unfamiliar, one option is to only introduce the acronym DES for discrete-event systems, and to refer to untimed distrete-event systems as untimed DES. Another option is to first introduce discrete-event systems, and then to subsequently introduce the acronym UDES for untimed DES.