The base book is also known as the "blue book" because it is blue?

The term "blue book" was originally used by the ancients in the process of printing books.

In ancient times, people called the engraved or movable type printed books as "version". Because the version of the book is generally printed in ink, it is also known as the "ink book". Ming and Qing dynasties, technological advances, the emergence of red, blue printing, respectively, called "Zhuyinben" "blue printing". This "Zhu printing this" "blue printing this" is not batch printing, but in order to print the template is good, after the publication of the first red or blue print out a few, used for proofreading, in order to correct the template errors, equivalent to the current printing process of the "proofreading". After finalizing the plate and then use ink to print the official batch printing. The book forest clear words" in: "its one color blue print, such as yellow mark "ink" fifteen volumes ...... this suspicion of the first printing samples, take to correct, not to blue print for the passage of the book also." Because these books are a book into the version of the initial printing, often called "the first printing of the red book" "the first printing of the blue book". And because of the "first printing of the blue book" is the most common, so, people will print the work of the base referred to as "blue book".

Later, the term "blue book" gradually evolved, no longer limited to the field of printing, extended to a general sense of the original reference.