## Source pages

The plug-in editor manages all three plug-in files at the same time.

The manifest.mf file is where all the plug-in data and dependencies is stored.

The plugin.xml file contains the extensions and extension points declared the plug-in.

The build.properties file contains all the information necessary to build the plug-in.

PDE validates the manifest.mf and plugin.xml for semantic errors and flags violations. The list problems that PDE flags are listed on the Plug-ins tab of the Plug-in Development > Compilers preference page:

You can set the level of each to one of Error, Warning or Ignore.

Note that for PDE to be able to detect some of these problems (e.g. required attributes not defined, undefined extension attributes, etc.), extension points you are using must have a valid schema associated with them. See Extension Point Schema for more details.