RG6 is the Society of Friends' Registers, Notes and Certificates of Births, Marriages and Burials ranging from 1578-1841.
Registers of births, deaths, burials and marriages of congregations of the Religious Society of Friends (Quakers) in England and Wales. A number of original birth and burial notes and original marriage certificates are included. The documents in the series are arranged by Quarterly or Monthly Meetings, which consisted of a county or combinations of counties.
With these RG6 records, it is important to remember that entries may be recorded in a number of registers, Monthly and / or Quarterly - but differences may occur and it is always worth viewing each record.
The Quakers had the reputation for maintaining the most meticulous records in keeping registers of births (Quakers did not practise baptism), marriages and deaths, as well as other records which related to their congregations, these being essential to record and ascertain membership of the Society.
Register books began to be kept by Quaker meetings from the late 1650s. Generally these registers were the responsibility of the Monthly Meeting and details were often compiled from independent records of the individual meetings. Sometimes, however, local registers were also kept by Preparative Meetings. To assist in their desire for parliamentary recognition of their marriage procedure under statute law, the Quakers developed a system of ceremony and registration which was so thorough that when Hardwicke's Marriage Act was passed in 1753, the Quakers were specifically excluded from the requirement to marry in Anglican churches.
In 1776, following a decision by the Yearly Meeting of 1774, the Quakers overhauled their whole registration system and introduced a more systematic procedure. Birth and burial notes were standardised with printed books being provided for Monthly and Quarterly Meetings.
The post-1776 birth notes and register entries contain the date of birth, place of birth (locality, parish and county), parents' names (often with the father's occupation), the child's name, the names of the witnesses, and are noted as a true copy with the signature of the registrar of the Meeting (for register entries). It is not always stated whether the father was living at the time of the birth. The post-1776 burial notes and register entries commence with the gravemaker's name and the date the grave was to be made, followed by the burial place and details of the deceased (name, residence, age, date of death), and concludes with the actual date of burial, and the mark or signature of the gravemaker (as witness).
All marriage certificates were transcribed at full length into Monthly Meeting registers, together with the names of witnesses. Quarterly Meeting registers were started consisting of printed forms of abstracts of the marriage certificates. In 1794, this requirement for Monthly Meetings to keep full copies of the certificates was rescinded, and from that date only the books of abstracts were kept by Monthly and Quarterly Meetings. These printed abstracts start with the date of the marriage, details of the groom (his name, residence and occupation), the groom's parents (including father's occupation), the bride's name, the bride's parents (including the father's occupation), the place where the ceremony was held, and conclude with signatures of witnesses the parties, and the registrar (or clerk) to the Meeting (for register entries).
You can find full details on TNA website, including content and background information.