Debian Policy Manual
Chapter 3 - Control files and their fields

Many of the tools in the package management suite manipulate data represented in a common format, known as control data. The data is often stored in control files. Binary and source packages have control files, and the .changes files which control the installation of uploaded files are also in control file format. Dpkg's internal databases are in a similar format.

3.1 Syntax of control files

A control file consists of one or more paragraphs of fields. The paragraphs are separated by blank lines. Some control files allow only one paragraph; others allow several, in which case each paragraph usually refers to a different package. (For example, in source packages, the first paragraph refers to the source package, and later paragraphs refer to binary packages generated from the source.)

Each paragraph consists of a series of data fields; each field consists of the field name, followed by a colon and then the data/value associated with that field. It ends at the end of the line. Horizontal whitespace (spaces and tabs) may occur immediately before or after the value and is ignored there; it is conventional to put a single space after the colon. For example, a field might be:

     Package: libc6

the field name is Package and the field value libc6.

Some fields' values may span several lines; in this case each continuation line must start with a space or tab. Any trailing spaces or tabs at the end of individual lines of a field value are ignored.

Except where otherwise stated only a single line of data is allowed and whitespace is not significant in a field body. Whitespace must not appear inside names (of packages, architectures, files or anything else) or version numbers, or between the characters of multi-character version relationships.

Field names are not case-sensitive, but it is usual to capitalize the field names using mixed case as shown below.

Blank lines, or lines consisting only of spaces and tabs, are not allowed within field values or between fields - that would mean a new paragraph.

3.2 List of fields

This list here is not supposed to be exhaustive. Most fields are dealt with elsewhere in this document.

3.2.1 Package

The name of the binary package. Package names consist of the alphanumerics and + - . (plus, minus and full stop).

They must be at least two characters long and must start with an alphanumeric character and not be all digits. The use of lowercase package names is strongly recommended unless the package you're building (or referring to, in other fields) is already using uppercase.

3.2.2 Version

This lists the source or binary package's version number - see Version numbering, Chapter 4.

3.2.3 Standards-Version

The most recent version of the standards (the policy manual and associated texts) with which the package complies. This is updated manually when editing the source package to conform to newer standards; it can sometimes be used to tell when a package needs attention. Its format is described above; see Standards conformance, Section 2.4.1.

3.2.4 Distribution

In a .changes file or parsed changelog output this contains the (space-separated) name(s) of the distribution(s) where this version of the package should be installed. Valid distributions are determined by the archive maintainers.[13]

Debian Policy Manual