This section is from the book "The Manufacture Of Boots And Shoes: Being A Modern Treatise Of All The Processes Of Making And Manufacturing Footgear", by F. Y. Golding. Also available from Amazon: The Manufacture Of Boots And Shoes.
The opening on the inside of a side-lace pattern should be situated about one inch from the sole edge, and should incline forward to allow the foot to be easily removed and replaced. The side lace, although not fashionable just now, is an exceedingly easy boot to wear, and is the pattern that will exhibit the skill of the designer the most. In Fig. 129, ab shows the opening for a side-lace boot.