Dealer Library Plan (DLP):

Under this plan, as agreement is reached between the library and the publishers or a group of publishers whereby the publishers send books as soon as they are published to the concerned library on specific subjects to selector reject them. It maybe worth noting  that  under the DLP, the library may get books earlier than the local booksellers. One of the advantages is that books published are  made  accessible immediately to the library for selection and procurement. However, one disadvantage may be that the library may receive books  not compatible with its particular requirements. This problem  can be overcome by the publisher  exercising care in sending books relevant to the organisation's interests. 

Standing Order:

Certain books called as Series books, Multi-Volumed books, Instalment books, and Subscription books are not published simultaneously but are published over a period of time in different years. Hence, individual libraries resort to the practice of placing "standing orders" so that the library receives the books as and when they are published without any loss of time.  This procedure eliminates

1) the need for watching out for publication announcements; and

2) correspondence with publishers/booksellers.