The first two paragraphs of this article are concerned with the general rule of competency of witnesses in both criminal and civil cases. Special considerations for the competency of children, spouses, and mentally ill are mentioned. It is emphasized that a witness must have personal knowledge concerning a matter and an understanding of the oath taken before the court. Paragraphs having to do with the oath are 603, 605, and 606. The concepts of 'oath' and 'sworn' are discussed in their affirmative connotation as is the ability of the court to invoke the contempt power upon refusal of a witness to swear or affirm. The testimony of judges and jurors as witnesses is not permissible in cases where they are engaged in a judicial capacity. Rules relating to the performance of interpreters in the courtroom are raised from paragraph 604. The last paragraph discussed is 615, which regulates witness exclusion from the courtroom.