§ 2 The Indefinite Article
As a rule a singular noun without any article expressed, except in the case of a noun followed by the appositional genitive, is considered to be in the indefinite state, and would be translated into English by a noun preceded by the indefinite article a or an. But partly as a corrupt following of English or French, and partly for emphasis, denoting a single one (like yr un in Welsh), the word a or an is sometimes represented by idn (earlier un), one. This is rare, especially in late Cornish. A similar indefinite article is common in Breton. Occasionally idn or un was used, as in Breton, with a verbal noun (or infinitive), to form what in English would be a present participle. Yn un scolchye, skulking, lit. in a skulking (Passion, 74, 2), yn un garme, shouting, crying out, lit. in a shouting (Passion, 168, 1), yn un fystyne, hastening, lit. in a hastening (Passion, 178, 1; 241, 4), but this construction is not found in late Cornish.