1. Grammar and Vocabulary
Overall effectiveness of accurate use of grammar and vocabulary
Do you know the rules well enough,
Do you know enough words?
Do you know the right words?
2. Discourse management
Coherence, extent and relevance of your individual contribution.
Flow
Does what you say flow?
3. Pronunciation
Stress, rhythm, intonation, individual sounds
Can a listener understand you easily?
4. Interactive communication
Can you keep a conversation going?
5. Global achievement
A general grade given by the interlocutor, that's the person telling you what to do in the exam.