The files are arranged chronologically within the series. The reference used consists of a set of numbers based on the monarch, regnal year, legal term and return day, except during the Interregnum period when it is based on calendar year, legal term and return day. Writs that were found loose and could not been reunited with their original files are collected at the end of the sequence for each monarch.
In the thirteenth and fourteenth centuries the writs within each file are arranged in a fixed county order, which is modified during the fifteenth century. The original county order is: Norfolk, Suffolk, Essex, Hertfordshire, Cambridgeshire, Huntingdonshire, Middlesex, London, Kent, Surrey, Sussex, Hampshire, Wiltshire, Somerset, Dorset, Devon, Cornwall, Herefordshire, Worcestershire, Gloucestershire, Oxfordshire, Berkshire, Buckinghamshire, Bedfordshire, Northamptonshire, Rutland, Shropshire, Staffordshire, Warwickshire, Leicestershire, Nottinghamshire, Derbyshire, Lincolnshire, Yorkshire, Northumberland, Cumberland, Westmorland and Lancashire (although as a palatinate Lancaster disappeared from 1351-1361 and then permanently after 1377). The modified fifteenth century order is: Norfolk, Suffolk, Cambridgeshire, Huntingdonshire, Surrey, Sussex, Essex, Hertfordshire, Middlesex to Derbyshire as previously, Northumberland, Cumberland, Westmorland, and (in any order) Yorkshire, Lincolnshire and Lancashire.
Letters to the justices and warrants of attorney, sometimes very numerous, come at the beginning of some files, before Norfolk, in files for return days at the beginning of term. Exigent writs or writs of exigi facias were filed before Oxfordshire.
From the early fourteenth century, there are two files for each of the first and second return days in the term. The first part consists of counties up to and including Gloucestershire; the second includes the rest of the counties from Oxfordshire onwards. From 1315 the second part is normally labelled 'Oxon' on its cover.
From Hilary term 1587, there are separate files for Middlesex and London for the first and subsequently the last return days. These additional parts have been numbered as 1A.
During the reign of Charles II, the first and last return days within each term are split into five parts, each group of counties there included was associated with a pictographic symbol: heart, ladder, crow, buckle or bell. These have been numbered respectively as 1, 1A, 1B, 2 and 2A.
During the reigns of George II and George III, a single file may cover more than one return day.