The only reference to 70B that I found is in the Handbook commentary:
The NEC is prepared by the National Electrical Code Committee, which consists of a Technical Correlating Committee and 20 code-making panels. The code-making panels have specific subject responsibility within the Code. The scope of the National Electrical Code Committee follows:
This committee shall have primary responsibility for documents on minimizing the risk of electricity as a source of electric shock and as a potential ignition source of fires and explosions. It shall also be responsible for text to minimize the propagation of fire and explosions due to electrical installations.
In addition to its overall responsibility for the National Electrical Code, the Technical Correlating Committee is responsible for the Electrical Code for One- and Two-Family Dwellings (NFPA 70A) and for the correlation of Recommended Practice for Electrical Equipment Maintenance (NFPA 70B), Standard for Electrical Safety Requirements for Employee Workplaces (NFPA 70E), Electrical Inspection Code for Existing Dwellings (NFPA 73), and Electrical Standard for Industrial Machinery (NFPA 79).