From the Backcover of 'An Introduction To The Sacred Language Of The Sikhs' By C. Shackle 

This book has been designed as a self-contained introductory course for anyone who wishes to gain a knowledge of the original language of the Sikh scriptures. Those to whom it is addressed are naturally expected to have an interest in and a concern for the teachings of Sikhism, but it has not been assumed that they will necessarily possess any specialized linguistic knowledge. It is also hoped, however, that users who do possess some knowledge of the modern language will benefit from working through the book.

The course is divided into three parts. Part 1 comprises a brief introduction to the Gurmukhi script, with the aid of a simple system of Roman transliteration. The aim has bean to teach the antique conventions of 17th century Gurmukhi spelling, which differs in some respects from modern Punjabi orthography. The script should be thoroughly mastered before proceeding further, since the use of the Roman script is later kept to a minimum.