this is not the easiest stuff, but it gives a little more insight in the matter.

You're welcome, BranShea. The past participial form of verbs in Old English used to be prefixed with the particle ge-. In Middle English this was reduced to a y-. Present-day English dropped it completely, except in some archaic forms like yclept, from clepe 'to call, name'. A similar change happened WRT the voiceless variety, OE h as in miht 'power', cf. NHG Macht, PDE might. This gh has several different realizations: e.g., enough, through, though, bough.

Ceci n'est pas un seing.