Classes should be given descriptive names. Avoid using abbreviations
where possible. Class names should always begin with an uppercase
letter. The PEAR class hierarchy is also reflected in the class name,
each level of the hierarchy separated with a single underscore.
Examples of good class names are:
Functions and methods should be named using the
"studly caps" style (also referred to as
"bumpy case" or "camel caps").
Functions should in addition have the package name as a prefix,
to avoid name collisions between packages. The initial letter of
the name (after the prefix) is lowercase, and each letter that
starts a new "word" is capitalized. Some examples:
Private class members (meaning class members that are intented
to be used only from within the same class in which they are
declared; PHP does not yet support truly-enforceable private
namespaces) are preceded by a single underscore. For example:
Constants should always be all-uppercase, with underscores to
separate words. Prefix constant names with the uppercased name
of the class/package they are used in. For example, the constants
used by the DB:: package all begin with
DB_.
If your package needs to define global variables, their name
should start with a single underscore followed by the package
name and another underscore. For example, the PEAR package uses
a global variable called $_PEAR_destructor_object_list.