The term “non-existent forms” is used here as an umbrella term for two main types of errors. First, errors in the use of possessive phrases where the definite article was used with a person as a possessor (as discussed in Chapter 8). In this aspect, low-rated theses contained significantly more errors (50) than high-rated ones. Second, to ensure the reliability of the analysis by accounting for all the items, we listed in the uninterpretable category all those instances that were mistakes and not errors that were not grammatical and could not be interpreted either as cohesive or non-cohesive.