VCDIFFFormat

VCDIFFFormat refers to the Variable-Chunk Differencing format, a standard for efficiently representing the differences between two versions of a file. It is defined by RFC 3284 and is commonly used for patch creation and application, particularly in software distribution and version control systems. The core idea is to describe how to transform one file (the source) into another (the target) by identifying common portions and describing the alterations needed for the differing parts.

The format works by identifying sequences of bytes that are common to both the source and target files, and then specifying instructions for inserting, copying, or deleting bytes. Instructions can include commands to copy a certain number of bytes from a specific offset in the source file, or to insert literal bytes from the patch data itself. This allows for a compact representation of changes, especially when files are very similar.

VCDIFF is designed to be efficient in terms of both storage space for the patch and the time required to apply it. It uses a delta encoding scheme that is flexible enough to handle various types of data. While it can be applied to any binary data, it is particularly effective for text files and structured data where small changes can result in large file differences. The format is widely supported by various tools and libraries for managing file differences.