One-letter contractions cannot be used as parts of words. No other letters or affixes may be attached.
Also, do and so cannot be used as notes, and must be spelled out. In the phrase Erin Go Bragh, Go must be spelled out.
They can, however, be used in English contractions, possessives, and hyphenated compound words.
These contractions cannot be used in words broken up as syllables or words hyphenated by a line break.
When these words are adjacent to each other, or adjacent to the word a (with no punctuation or capital symbols in between), no intervening space is required.
No letters, affixes or punctuation may be attached to these contractions, but can be used with capital symbols or italics.
When there isn't enough space on a line to attach these symbols to the next word, spell out the preposition and set the next word on the next line.
These prepositions may be used after punctuation and before a capital sign, but not before punctuation or as part of a compound word.
To can be combined with in to form into, which is subject to the same rules as to is.