6d026765_Plugin_YAML___BukkitWiki_Attributes_Notes
[Attribute] softdepend [Required] no [Description] A list of plugins that are required for your plugin to have full functionality. [Example] softdepend: [OnePlugin, AnotherPlugin] [Notes] 
The value must be in YAML list format (See http://en.wikipedia.org/wiki/YAML#Lists ) Use the "name" atrribute of the desired plugin in order to specify the dependancy. Your plugin will load after any plugins listed here. Circular soft dependencies are loaded arbitrarily. (See: Wiki: Plugin_Dependencies)
Plugin YAML - BukkitWiki
Notes