Domain includes knowing your rights and responsibilities in any discussion in which you may be participating. Is the discussion of a personal nature? Are you being interviewed for a job?
In each of these instances personal questions need to be answered in different manners. If the conversation is of a personal nature you can feel free to answer any question you want. On the other hand, if you are interviewing for a job, personal questions concerning your family, personal preferences, etc. might well be out of place.
The same is also true for the workplace. Certain questions may be asked and answered depending on the relationship between the speakers.
Register Use
Register use refers to the type of language you should use depending on the relationship between you and the speaker. Is the person you are speaking with a subordinate, or is he / she your boss? Do you have a friendly relationship with this person? Is joking allowed?
In general, the more informal the situation the more informal the language can be. Generally, colleagues in the US go by a first name basis and also use more colloquial language with each other. If, on the other hand, you are speaking with a supervisor you will probably use more formal language for example: Ms. Smith
Urgency
Urgency concerns the importance of your message. This urgency will also be reflected in the language you choose to use. If the message is extremely important, and you are speaking with a subordinate (register use) the imperative form (i.e. Call Mr Jackson!) might be appropriate. On the other hand, if your message is not so important and you are speaking with a supervisor, you would use more formal forms to get that person's attention (i.e. Excuse the interruption Mr Brown, but would you mind taking a look at this report when you have the time?).
Once again, the tendency in the American workplace is for more important (urgent) messages to be expressed in simple direct language. The less important message are often softened with more formal language.
Explore useful phrases and proper language use in these business English articles:
Introduction and Example Meeting Dialogue
Phrase Reference Sheet for Participating in a Meeting
Phrase Reference Sheet for Running a Meeting
Formal or Informal? Appropriate Language in Business Situations
