NGS' Blue Book is explained.

The National Geodetic Survey created “Input Formats and Specifications of the National Geodetic Survey (NGS) Data Base,” a user’s guide for preparing and submitting geodetic data for incorporation into NGS’ database. Commonly called the “Blue Book,” the guide includes Volume I, which covers classical horizontal geodetic and GPS data; Volume II, which covers vertical geodetic data; and Volume III, which covers gravity data. Survey data that are entered into NGS’ database become part of the National Spatial Reference System (NSRS), formerly known as the National Geodetic Reference System.

Survey data that are submitted to NGS for incorporation into NSRS should be properly formatted and supply minimum accuracies of: first-order horizontal accuracy standards for GPS and conventional horizontal surveys; second-order, class II vertical accuracy standards for conventional leveling; and third-order gravity standards for gravity surveys. These surveys must contain connections to NSRS in accordance with FGDC Standards and Specifications, and they must contribute to the public good.

The Blue Book is now updated as needed, and is only available from the NGS website. For more information, visit, click on Product and Division pages, FGCS/GIAC, Publications and Presentations, Input Formats and Specifications of the National Geodetic Survey.