12.6.1 Alphabet and accents
Both Irish and Scots Gaelic are written in an eighteen-letter alphabet with no j, k, q, v, w, x, y, z (except in some modern loanwords); in Irish the lower-case і is sometimes left undotted. Until the middle of the twentieth century Irish (but not Scots Gaelic) was often written and printed in insular script, a medieval form of Latin handwriting, in which a dot was marked over aspirated consonants. In Roman script aspirated consonants are indicated by the addition of h after the letter, in both Irish and Scots Gaelic (Irish an chos ‘the foot’, Scots Gaelic a’ chas). Irish marks vowel length with an acute accent (á, é, í, ó, ú), Scots Gaelic with the grave (à, è, ì, ò, ù). Apostrophes are frequent in Scots Gaelic, less so in Irish.
In Irish Gaelic, as in Scots Gaelic and Welsh, initial consonants are replaced by others in certain grammatical contexts, in a process called mutation. In Irish the mutation known as eclipsis is indicated by writing the sound actually pronounced before the consonant modified: mb, gc, nd, bhf, ng, bp, dt. If the noun is a proper name, it retains its capital, the prefixed letter(s) being lower case:
na bhFrancach ‘of the French’
The same combination of initial lower-case letter followed by a capital occurs when h or n is prefixed to a name beginning with a vowel— go hÉirinn ‘to Ireland’, Tír na nÓg ‘the Land of the Young’—or t is prefixed to a vowel or S: an tAigéan Atlantach ‘the Atlantic Ocean’, an tSionnain ‘Shannon’. Before lower-case vowels, h is prefixed directly (na hoíche ‘of the night’), as is t before s (an tsráid ‘the street’), but n and t take a hyphen before a vowel (in-áit ‘in a place’, an t-uisce ‘the water’). Except in dialects, eclipsis is not found with consonants in Scots Gaelic.
Prefixed h-, n-, and t- always take a hyphen:
an t-sràid ‘the street’
Ar n-Athair ‘Our Father’
na h-oidhche ‘of the night’
na h-Eileanan an Iar ‘the Western Isles’