Library Reinforced Binding:

Reinforced binding means strengthening the book by adding some material. It could be strengthening of the hinge with cloth or the reinforcing a pale with some tissue. 

The Council of the American Library Association, the Library Binding Institute (L the Joint Committee of A:L.A, have  prescribed the standards for Re-inforced (pre-library bound) binding of new books as follows: 

1)  All 'reinforced' new books shall be completely renewed in accordance with the minimum specifications for class 'A'  Library Binding. (Most  books having proper inner margins and suitable paper shall be sewed by machine, all sections shall be pasted. No oversewing shall extend more than 3/16 inch in from the backedge of the volume, and no nearer to the head and tail than 1/2 inch). 

i) With the exception of the cover, all other parts, construction, processes and materials. shall be in conformity with the minimum specifications, 

ii) Three types of cover shall be permissible: 

Type I Class 'A' Cover. Cover similar in appearance to the  publishers' original cover but made of heavy weight library buckram (starch filled of pyroxlin-filled) or pyroxlin coated fabric as required by the minimum specification, and with the publisher's original design imprinted thereon.  

Type II Publihser's light-weight buckram cover. Cover similar to that of Type I, but made of a light-weight  buckram, with the publisher's original design imprinted thereon. 

Type III Publisher's original cover. This refers to the cover which would be on, the book if  bought in its original form, non-reinforced, through the  usual channels. A reinforced book of this type would have the publisher's original cover taken off by the binder, who would then resew and otherwise reinforce the book and replace the original cover on: the volume.