The syntax to refer to another resource in the XML file is
The package is optional and is not required when access the resources in your owner package.
The package we often used is android.
color #color resources; saved in res/color
drawable #bitmap, png graphics and frame animation ; saved in res/drawable
layout #layout ; saved in res/layout
menu #contents of your menus; saved in res/menu
string #string, stri... (more)