The package definition file package.xml is,
as the name already implies, a well-formed XML file that contains
all information about a PEAR package. Version 2.0 contains several important
enhancements over version 1.0, including
Channel support
Binary PECL packages support (not fully implemented in PEAR 1.4.0)
More specific dependency resolution
For those of you with an existing package.xml version 1.0, you can create an approximate
equivalent package using the
$ pear convert
command. Note that as of version 1.6.0a1, PEAR_PackageFileManager supports package.xml
2.0 with the PEAR_PackageFileManager2 class.
PECL developers: for more information on pecl-specific features,
read here.