The control data might be enclosed in an OpenPGP ASCII Armored signature, as specified in RFC4880.
The name of the .buildinfo file will depend on the type of build and will be as specific as necessary but not more; for a build that includes any the name will be source-name_binary-version_arch.buildinfo, or otherwise for a build that includes all the name will be source-name_binary-version_all.buildinfo, or otherwise for a build that includes source the name will be source-name_source-version_source.buildinfo.
The first line of the field value (the part on the same line as the field name followed by a colon) is always empty. The content of the field is expressed as continuation lines, one line per file. Each line consists of space-separated entries describing the file: the checksum, the file size, and the file name.
These fields list all files that make up the build.
On Debian and derivatives only build paths starting with /build/ will emit this field.
The list consists of each package name, optionally arch-qualified for foreign architectures, with an exact version restriction, separated by commas.
The list includes all essential packages, packages listed in Build-Depends, Build-Depends-Arch, Build-Depends-Indep source control fields, any vendor specific builtin dependencies, and all their recursive dependencies. On Debian and derivatives the dependency builtin is build-essential.
For dependencies coming from the source control fields, all dependency alternatives and all providers of virtual packages depended on will be included.