# Feature Bits by Category - Overview

The following pages summarize all feature bits according to category (as presented in the Web Console). The category numbers are not used for FCOS configuration input, but are provided for reference when designing an FCOS.

Primary feature bits appear in bold type. Not all categories have primary feature bits. Some feature bit categories require optional feature software, which is described in the summary for each category. Other categories require optional feature software for specific feature bits, only. This is noted by an asterisk (*) at the beginning of the feature bit description. Certain feature bits require that a recipient’s mailbox contain “message receiving feature bits,” such as those listed under Category 7. Those feature bits are listed beside the required feature bits for making and sending messages. Refer to the Feature Bit Descriptions section for detailed information about each feature bit.