affairs only. Suspicious looking letters - may be exposed to heat or treated in any other suitable manner as a safeguard against unauthorised messages written in invisible ink being smuggled in or out of prison. Retention of letters by prisoners: Rule547. A prisoner may unless the Superintendent otherwise directs retain any letters which may have been delivered to him or may request to these be kept for him in the prison. Interview or communication to take place without permission of Superintendent: Rule548. No prisoner shall be allowed to have an Interview or to write letter except with the permission of the Superintendent, which shall be recorded in writing. Provision of writing materials: Rule549. Writing materials, including service post-cards shall be supplied to any prisoner permitted to write a letter and all letters shall be written at such time and place as the Superintendent may appoint. One day in the week, preferable Sunday, shall be set apart for letter writing. Service postage stamps at Government expense shall be provided for prisoner's letters. Letters and interviews, etc., to be recorded on history tickets: Rule550. (i) Interviews and letters allowed to a prisoner shall be entered on his history ticket and initialled by the Superintendent or by an officer deputed by him. (ii) Every interview shall also be recorded in the interview register and entries shall be initialled by the Deputy Superintendent and Superintendent. (iii) All petitions, vakalatnamas and notices sent or received by prisoners shall be entered on the history tickets. All registered letters and parcels received by prisoners shall be similarly recorded. Petitions for interviews: Rule551. Request for interviews with prisoners may be oral-or in writing at the discretion of the Superintendent. A prison official, to be deputed by the Superintendent, shall record the names of the interviews and prisoners in the interview register. If the prisoner is not entitled to an interview, the applicant shall be informed at once by the Assistant Superintendent or other officer incharge of interviews. [Explanation, -while recording interviews number of the identity card of the interviewer shall also be entered in the Interviews register. No visitor shall be allowed to have interview without showing the identity card]. Time and days of interview: 190