9. A method according to claim 2 including the step of storing an indication in association with the words in the low frequency file, of whether the words are principal and/or participating words in limited semantic compounds.
13. A method, according to claim 9, in which during scanning and comparing with dictionaries, information is attached to the principal word concerning all the compound expressions within which the principal word may function as key word in a compound, the attached information containing either sequences of limited semantic numbers or an address of an auxiliary storage device where such information is located, and including the additional steps of bringing into a main working memory from the auxiliary storage device during analyzing the file of words, the limited semantic numbers assigning a subject field code to the source text, if the same compound expression of the source language indicated by the limited semantic numbers have different target meanings, then selection of the correct meaning for the compound depending upon the subject field code in which the translation takes place.