The name "Existence" is confusing and may be need to be changed. It contravenes the general requirement of the ISA hierarchy that sub classes may be described by the form "X is a Y". "Stuff is an Existence", for example, stretches comprehension into the realms of speculative metaphysics. Placing the accent on persistent identity rather on existence may provide an acceptable alternative: "Persistent Item", for example, or possibly just "Thing". However, this would appear to create some overlap with the E70 Stuff (cf scope note).
I would suggest renaming E70 Stuff to emphasise the notion of potential use, (which is the only attribute introduced by this entity) "Useable Thing", perhaps. Apart from being disarmingly colloquial the term 'stuff' is arguably inappropriate since the scope note clearly indicates that the entity is intended to encompass 'items' - the word "stuff" suggests (at least to me) undifferentiated material rather than persistent, identifiable and useable items.
NC 18 January 2002
1. Proposal to rename "E77 Existence" as "E77 Persistent Item" accepted.
2. Proposal to rename "Stuff" rejected. There seems not to be any alternative term that may be closer to the intended meaning.
Monterey 21/2/2002.