Experiments with interpretation of the labels. The label otol.

[Anton]

Therefore I asked what about the words ol, ot, or, etc. Is "o" in them an operator

I think it would not be, since, as I said, they appear to be kinda "core" bigrams.

If not, how to identify words where "o" is a prefix that plays role of a preposition or a conjunction, for example, and where it is just a letter or just a prefix?

That may be not that complex.

There are (ref. VQP) 8558 vords starting with "o", i.e. "o*" wildcard (neglecting standalone "o")

Of those:

2417 are ot*
2474 are ok*
360 are op*
240 are od*
89 are of*

(these are pre-gallows and pre-d), the subtotal is 5580 or 65%. I'd say these are all operators.

Next, there are:

1069 ol*
244 or*
538 ol (just two-character vord)
366 or (just two-character vord)

the subtotal is 2217, or 26%

I guess that ol* and or* are composites here, - in other words, "o" is not an operator here.

What remains are 661 occurrences, such as 173 oc*, 132 oe* etc.

So my first guess would be that every vord-starting o beyond that in basic bigrams ol and or is a relational operator.

If we leave the particular relatonal prefix theory and instead consider o as some specific marker (which is a more "generalized" approach), the above considerations would still hold.