Spelling

The means by which letters are formed to make words.

However, it must be noted that what constitutes a word in the above definition is not negotiable. If it's in the OED, it's a word. If it's not in there, it's not a word. Unless you're writing in a language other than English, of course. As the days of Empire are over, you can probably get away with that.

PPC Agents make many sacrifices to the gods of orthography, lest they not be sufficiently appeased, and show their wrath by raining fire and brimstone on all and sundry. These sacrifices are usually in the form of Sues or Wraiths.