PHP constants are defined using %<constant>% tags. The actual constant name, type and value are specified using the %name%, %type% and %value% attributes. Valid types for a constant are %int%, %float% and %string%. For %int% and %float% you may use either numeric strings or the names of C constants (either true ANSI C/C++ constants or values #defined using the C preprocessor. %string% values are always used "as is", no constants may be used here. If only the %name% attribute is given it is assumed that the constant is supposed of type %int% and that its value is to be that of a C constant of the same name. A descriptive text may be given as data content of the %<constant>% tag. This text will be used when generation the DocBook XML documentation.