"In Standard Breton and in L, the infinitive is dleoud, stem dle-, derived from dle ‘debt’, cf. Welsh dyled ‘debt’ and modal auxiliary dylai ‘should, ought’, and Irish dlí ‘law’. The initial consonant cluster dl- is unstable in Breton; three resolutions are possible: (1) insertion of an epenthetic vowel, as in G: dële ‘debt’, dëleein ‘owe; must, ought to’; (2) loss of d-, as in dluzh ‘trout’ > T luzh; and (3) dl > gl, as in widely in T and K: gle ‘debt’, gleoud ‘owe’. On the analogy of dle > gle, the ‘mixed’ (lenition/provection) mutation applied to the stem dle-: …e≠tlean [AFF I.must/ought], the tl- cluster became kl-, and then this was interpreted as being the basic, unmutated form for the modal auxiliary but not for the lexical verb, so in T there is now gleoud, gle-, ‘owe’ (43a) gleoud a ran arc’hant dit owe.INF AFF I.do money to.you ‘I owe you money’ (43b) me a =c’hle arc’hant dit I AFF oweº money to.you ‘I owe you money’ but klea’ , kle- ‘must, ought’ (44a) klea’ a ran mond must.INF AFF I.do go.INF ‘I must go’ (44b) me a =gle mond I AFF must go.INF ‘I must go’ Guillaume Floc’h informs me that in Plouhineg, south of Gẘaien (Audierne), the lexical verb is lea, le- < dleoud, dle-, but the stem for ‘must, ought’ is tre- < tle-. So in many areas of Brittany, a morphological distinction is made between the stem for the lexical verb ‘owe’ and that for the modal auxiliary ‘must, ought’."