My thanks go out to Themis ....found this in my notes.
By Themis --A deposition is a pre-trial discovery/trial preparation method. It is essentially an interview of a potential witness, placed under oath, and transcribed by a court reporter. It is not done in the presence of a judge. It differrs from an interview because the witness is under oath and the statements made by the witness can be used as a prior sworn statement to impeach the witness at trial. Depos are noticed to the other side and they are allowed to attend and ask questions. The witness may also bring an attorney to consult with, but the witness attorney does not ask questions, just consults with the witness privately. Anyone can record the deposition (like taking notes) but only the court reporter's transcript is the official record of the deposition. The witness gets a chance after the deposition to review the transcript and make end notes, like "Page 4, paragraph 7, I recall testifying that the light was not red. The transcript states I testified that the light was red. This is called an errata sheet or comment sheet. The deposition and errata sheet become part of the record. If there is a substantive dispute like that, the attorneys who scheduled the depo may want to re-open the depo to ask further questions in that area. Otherwise, the audio and typed record of the court-reporter are the only official record to be referred to to resolve a substantive dispute. Depositions are generally taken to preserve the testimony of a witness in the event a witness becomes unavailable for trial. Some of the reasons a witness may become unavailable for trial are: the witness is in ill health and dies before trial or is too ill to attend the trial (physical unavailability), the witness moves out of the jurisidiction and beyond the subpoena power of the court (geographic/jurisdictional unavailability), the witness states they can't remember certain things and the depo can be used to refresh their memory at trial (mental unavailability), or the witness may be subject to charges or otherwise have a right to and does claim the 5th amendment right to remain silent (that is a legal unavailability). If a witness is subpoenaed for a deposition and refuses to show up or is belligerent in refusing to answer questions and that refusal is not based on a legal privilege or the 5th Amendment rights to remain silent because what is asked calls for an answer that may incriminate the witness, then the remedy is to make a motion in court to compel the witness to answer. Once the witness is ordered by the court to answer the question(s) and does not, the witness may be subjected to an Order to Show Cause why the witness should not be held in contempt of court; exposing the witness to possible incarceration and heavy fines.