The independent form is used when no particle precedes the verb, as in Chonaic mé Seán ("I saw John").
[n 2] The distinction between dependent and independent forms originates with two distinct but related phenomena in Old Irish: the contrast between absolute and conjunct verb endings, and the contrast between prototonic and deuterotonic forms.
(An interpunct "·", hyphen "-", or colon ":" is usually used to indicate conjunct forms in pedagogical and analytical works on Old Irish.
As can be seen in the above examples, the phonological effects of stress placement can be significant; for example, when the prefix com- follows the stressed syllable, it is reduced to just n. These phonological changes become even more apparent when a conjunct particle like ní ("not") is added.
In this case, stress shifts to the first prefix, which has phonological consequences for the rest of the verbal complex.
The relationship between prototonic and deuterotonic compound verb forms is thus analogous to that between simple verb forms with conjunct and absolute endings: the one group is used after a conjunct particle like ní, the other group without such a particle.
[2]: 479 This form survives in Modern Irish as fuil, in Gaelic as (bh)eil, and in Manx as nel/vel, all of which are used as the dependent equivalent of the verb for "is".
Gaelic glac and Manx dilg above[n 4]) were gradually being replaced by forms with the ending -(e)ann.
Realis clauses indicate conditionals with a possible fulfillment (e.g. "if he is agreeable", which leaves open the possibility that he is), while irrealis clauses indicate purely hypothetical conditionals (e.g. "if it were a nice day", but it isn't).