Compose has a language all its own.  This page will help you make sense of it.

There are twelve blocks containing various parameters and settings.  Here's what they are, broken down by the sub-tabs that they appear on:

• Tracks sub-tab - This section deals with the arranging and editing of the motions.  In other words, this is where you decide which clip will be used when, and for how long, and how it will blend with other clips.

Clip Instance - The Clip Instance block allows you to modify the parameters of the Clip Instance.  You can have multiple instances of a clip by copying or inserting them onto the Tracks.
Factors - This is sort of like a "Setup Mode" for Motion Clips.  It lets you tailor the default positions of the items with regard to the motion in the Clip.  For example if you have a Clip that was made from a tall character and you are now applying it to a short character, this is where you would make the necessary adjustments to fit the data in the Clip to the character.
Group - This block lets you give custom names to each Character Group and keyframe its "strength"-- the degree to which it will be used.  You can also load and save a complete performance here.
Record - The Record block is where you record motion Clips.  "Record" can also be thought of as "capture" because it is "capturing" the motion and creating a Clip out of it.  On the Tracks sub-tab this will record the motion and assign it to the objects that it got the motion from, then it will create a Track for the clip and put an instance of the clip there.
Spline - The Spline block is used to make adjustments to the motion spline.  Using the settings here, you can control what happens around the keyframes, for example, how the motion should ease in or ease out, or whether it should stop after the last keyframe or repeat the motion.
Track - The Track block lets you give custom names to each track and keyframe its "strength"-- the degree to which it will be used.

• Clips sub-tab -  This section deals with the Clips themselves, as well as the motions contained within those clips.

Bake - The Bake block allows you to take motion from Compose and "bake" it back onto an object.  In other words, after you finish creating the motion you want with Compose-- which could be made up of several different Motion Clips-- you can take all of that data and place it into the object's Motion Path so it will no longer need Compose.
Clip - The Clip block allows you to globally replace or delete a clip.  That is, everywhere that it is used in the scene.
Record - The Record block is where you record motion Clips.  "Record" can also be thought of as "capture" because it is "capturing" the motion and creating a Clip out of it.  On the Clips sub-tab this only records the clip, it doesn't assign it to any objects.
Spline - The Spline block is used to make adjustments to the motion spline.  Using the settings here, you can control what happens around the keyframes, for example, how the motion should ease in or ease out, or whether it should stop after the last keyframe or repeat the motion.
Values - The Values block is tied in with the Motion Graph in the same way that the Motion Block on the Animation tab is.  You use this to set values for keyframes.

• Groups sub-tab - This is where Character Groups are set up and maintained.  This block is the same one that appears in the Groups sub-tab of Setup.  You can use either one.

• Match sub-tab - The Match sub-tab is where you assign a clip's motion to the object(s).  The idea is that a Group is matched to a clip and each element within the Group is matched to an element of the motion clip (the motion clip might contain the motion of several objects, and even multiple characters).  You have several choices about how to do that, but what it basically comes down to is that you can assign it to the same objects that it was clipped from, or to other objects.  For example, you might animate a ball bouncing and make a clip of that motion.  You can then assign that motion to the ball (which it already will be by default) or apply it to a different object.  This is extremely useful because it allows you to do things like clip the walk cycle of one character and apply it to another character.

Compose has a language all its own, some of which might need a little explaining.  Don't worry about memorizing them; in fact don't worry about any of this.  Turn off your computer and go play in the sun!

Note: Several of these definitions, such as Active/Bypass, apply to other aspects of messiah and are explained elsewhere, but in the interests of completeness, I've included them here as well to make the list look long and scary.

• Active/Bypass:  This is a toggle to allow the motion to be used, or to be bypassed (not used).  The toggle works just like the ones for Effects, Shaders, etc.  Green means it's active, and red means it's bypassed.  Click here for more information and a picture.
• Bake:  When you "bake" a motion, you are taking the modified motion (motion from Compose and/or any other effects or expressions that are acting upon the motion) and converting it to keyframed motion that contains all of the modifications.  Or to think of it another way, it takes the entire motion, including any outside forces, and makes them "built in" to the motion.
• Blend: If you have two different clips and you want to transition from one to the other you use a Blend.  The Blend can be keyframed too, so you can control how that transition happens.
• Character Group: See Group.
• Clip: Also called Motion Clip.  A Clip is motion that has been captured from one or more items.  They can be loaded and saved
• Clip Instance:  A Clip Instance is a reference to an actual Clip.  You adjust the length and position of the Clip Instance on the Track Timeline but you're not actually affecting the real clip.  In other words, the Clip Instance looks at the Clip and says "this is what my motion is" and then you can adjust the Clip Instance so it plays that motion faster or slower, or loops or doesn't loop, etc.  If you modify the actual clip (on the Clips sub-tab) it will automatically apply to the Clip Instances that are referencing that Clip.  But modifying a Clip Instance will not do anything to the Clip.
• Clip List:  When you are on the Clips sub-tab, the list running down the left side of the interface is the Clip List.  You can expand and contract the things that appear on this list.  For example, you can expand the channels of an object, then select a channel and edit it in the Motion Graph.
• Element: This can refer to two things:  a member of a group (object, light, camera, channel, etc.) or a motion within a clip (the camera's motion, a specific object's motion, a channel's motion, etc.).  Generally you can tell what it's referring to from the context it's mentioned in.
• Group: Also called "Character Group".  A Group is a collection of items (objects, lights, individual motion channels, etc.) that you choose to think of as a family, or group.  Of course it can also be just one item.  For example character A can be one Group, and character B can be another, while the Camera is its own group.  If you want, everything in the scene can be part of one group, though it's extremely rare that you would want to (or need to) do that.
• Group List:  When you are on the Groups sub-tab, the list running down the left side of the interface is the Group List.  It shows you every Group in the scene as well as every member within that group (using the right side list, which is sometimes called the Group Member List).
• Locked/Unlocked:  When a track is locked (lock icon in the Compose List) you won't be able to do anything to it (until you unlock it).
• Match: Matching is when you take an item and match it to a motion.  Usually when you record a Motion Clip it will automatically match the objects with the motions.  But sometimes you may want to change the matching.  For example, you might want to apply the walk cycle Motion Clip of character A to the objects of character B.
• Match List:  When you are on the Match sub-tab, the list running down the left side of the interface is the Match List.  There are actually two lists that make up the Match List.  On the left is a list that shows the items within the current Group, and on the right is the motion Match for each of those items.
• Member: A member is a part of a Group.  Groups are made up of one or more members, such as objects, lights, cameras, etc.
• Motion Clip:  See "Clip."  Or don't; it's up to you.
• Motion Compensation: Motion Clips contain not only the keyframe information, but also the Rest information for each item.  When you apply a Clip to a character, you need to be able to decide if, or how, to compensate for animation that may exist on the objects.  The "if" there is in reference to whether the character and its components are situated at their rest positions (or not) at the frame you want to insert the Clip.
• Motion Composite Operator: (also called just "Composite Operator" or "Blend Operator") This set of click-through options lets you choose how you want the motion to be applied with regard to any existing motion that is already on the item.  Click here for more information and a picture.
• Motion End Behavior:  (usually just called "End Behavior") Choose what you want to happen at the end of the motion in the Clip.  Click here for more information and a picture of the choices.
• Performance:  A Performance is a collection of different clips that you have arranged on the Track Timeline.  You can save Performances and use them again later.
• Pin (Pinned): When a Clip Instance is "pinned" it will stay on the Track Timeline even when you are working with a different Group.  This can be useful if you need to match the timing, or at least know when a Clip on a different Group.  The pinned Track/Clip Instances will not affect the motion of the active Group, they're just there for visual reference.
• Processing Order: (sometimes called Solving Sequence or Solving Order) refers to when you want the motion to be applied.  The choices are Apply After Motion, which will let all motion on the group calculate first, then apply the motion from the Clip Instances; Apply Before IK, which will apply all of this before the IK is calculated; and Apply After IK, which will apply it after the IK calculations are made.
• Record: Record will capture the motion from the selected item(s) and create a Clip which can then be applied to items within your scene.  They can also be loaded and saved to create motion libraries for future use.
• Track:  A Track is where you place and arrange Clip Instances.  On the Track Timeline you will see it as a horizontal area where you can place one Clip next to each other.  By default you can only view the Track(s) for one Group at a time, but if you want to make a Track from one Group visible while a different Group is active, turn on the pushpin icon for that Track in the Track List or on the Track Timeline.
• Track List:  When you are on the Tracks sub-tab, the list running down the left side of the interface is the Tracks List.  This shows all of the Groups, Tracks, Clip Instances, along with the items and channels within each Clip Instance.
• Track Timeline:  The Track Timeline appears above the Motion Graph, below the World View when you are on the Compose tab.  This is where you arrange your Tracks and the Clip Instances within them.  Keep in mind that it is the Clip INSTANCES that you are working with here, not the Clips themselves, so changes that you make will not affect the actual Clips.  This is a good thing because it means that you can use one clip in several different ways.  For example, a clip of a bouncing ball can be used in two places, and one time it can be made to bounce fast, and another time slow.