BCOS File Type Specification

Chapter 1: Introduction

For the BCOS project, files are given standard file types so that software can easily determine the file format used by the file without guessing.

1.1. File Type Numbers

A 32-bit file type number is split into a pair of 16-bit components. The first 16-bit component is the "file type major" which specifies the type of data (e.g. graphics data, text data, an executable file, etc) and the second 16-bit component is the "file type minor" which specifies the exact format for the file. For example, the file type major might indicate that the file contains graphics data, while the file type minor would indicate if the file is in the OS's native graphics file format or a JPG, a GIF, a BMP, etc. For all native file formats except for special OS specific system files, the file type minor is always zero. For special OS specific system files (which all use native file formats) the file type major is always 0xFFFF, however these file types and file formats aren't intended to be used by normal applications.

1.2. File Type List

The list of file type numbers (Table 1-1. File Type Numbers) is the authoritative list of all valid file type numbers, including a link to the specification that defines each file format where possible.