The previous murage had been granted 2 May 1367, less than four years before. The monitoring of when grants were due to expire does seem to have caused trouble from time to time. Roman numerals, various calendars, regnal years, dating based on movable feast days can cause modern readers some difficulty. Medieval town clerks would have been more familiar with these things but would also have to cope with manuscript parchment rolls (often written in a very tiny hand) and a lack of good artificial light.