(alternate transliterations include Sikh Rahit Marayada and Sikh Reht Maryada is the Sikh Code of Conduct which was put into force right from the birth of Sikhism.
In 1915 and later in 1931, attempts were made to create a modern standard Rehat (Rehat or code). This effort involved several Sikh scholars who worked to produce the current version. In 1950 the “Sikh Rehat Maryada” was finally approved. The document has been accepted as the official version which provides guidelines for all Sikh individuals and communities around the world. Its implementation has resulted in a high level of uniformity in the religious and social practices of Sikhism.
Sikh Rehat Maryada is based on earlier codes (Rehat namas), the earliest of them are:
1. Tanakhah-nama (Nasihat Nama) Samvat 1776 (1718-19 CE), ten years after the death of Guru Gobind Singh.
2. The Prahilad Rai Rehat-nama
3. Sakhi Rehat ki: About 1735 CE
4. Chaupa Singh Rehat-nama: 1740-1765 CE (1700 CE according to Piara Singh Padam). Chaupa Singh was a member of the Guru’s retinue. He was entrusted with the care of infant Gobind Das by Guru Tegh Bahadur. Some members of Chaupa Singh’s family became martyrs with Guru Tegh Bahadur in Delhi and others served under the 10th Guru.
5. Desa Singh Rehat-nama: late 18th century
6. Daya Singh Rehat-nama
Read more on wikipedia Sikh Sikh Rehat Maryada Articles
SGPC Sikh Rehat Maryada link