# HIRC Objects (Advanced Guide)

<p class="callout info">See [Audio Length (Advanced Guide)](https://wiki.eternalmods.com/books/beginners-guide-how-to-create-mods/page/sound-length-advanced-guide) before proceeding.</p>

## HIRC (Hierarchy) Objects

These are the components to the PCK files. They are separated by **&lt;object&gt;** in the exported XML document.

##### **Music**

#### Attenuation

Determines the force reduction of the overall audio. It is measured by "Curves" which can be scaled by "GraphPoints" using an "Interpolator".

#### MusicTrack

Actual components to each individual music track. It determines the "Duration" and "TrimOffSets" of the track.

#### MusicSegment

Immediately following a "MusicTrack" is its "MusicSegment". It also determines the "Duration", but it establishes "Music Markers" which actuates when the track starts and ends.

#### MusicSequence

Contains the list of all "MusicTracks" that will play in the sequence. It determines the the "TransitionRules" and "Destination Rules" for each Music Track.

#### MusicSwitchContainer

Decides when the "MusicTracks" start playing. It is structured much like a "MusicSequence".

#### EventAction

Directly responsible for starting and stopping the music.

#### Event

Immediately following an "EventAction". This is the individual event that holds the ID which will start or stop.