Apropos of "finding the right exposition"!, consider the cited wiki article:
Separator: There is a symbol between each element.
The more carefully you read this the more it becomes nonsense.
1, "Each element" is an individual. You can't put something between an
individual.
2 The defining sentence states a property of a representation of a
sequence. It fails to indicate that "separator" is the symbol's role.
In fact what's being defined is "separator notation", not the bare
word "separator". This usage appears only later in the article. It
should be employed throughout--most importantly in the title and the
definition. The same goes for "terminator".
Doug