This is how it turned out...

So this is how it turned out. It has common wildcards for control names, a textfield to enter combinations of control names or animated objects which may not be controls. The list will only show objects which have animated attributes. If "none" is selected, all the animated objects in the scene will be listed.

For saving animation, the saver will by default save the animation for everything in the list. If you select objects from the list, it will save animation only from those objects, and only on channels that are animated.

There is an option to save animation only from the selected referenced character, so if there are multiple characters in a scene, only the selected reference gets saved. This is currently only a single selection option, but if there's a need, I can make it multiple selection.

I've added an "Animation Offset" option, which allows animation that may not start until the middle of the scene to be synchronized with the scene on load, and a "Motion Capture" option for saving, which makes for file sizes that are 25% or less the size of the full animation file which has weight and tangent information.

I also added a "No Character Reference" mode, so that animation can be transferred to and from characters which are not referenced, as many files coming to me through motion builder haven't been referenced yet. When "No Character Reference" is checked, the text that says "Reference Character Controls" changes to "Character Controls".

The remapper automatically loads the available animated channels from the file on read into the left hand column below in the "Anim File Controls" column, and selecting a character from the "Reference List" above automatically loads its available objects based on the "Select Wildcard" choices at the top of the interface (including the wildcards entered into the text field).

I've also made the selection process much faster. A single click on either of the objects in the "Anim File Controls" or "Reference Character Controls" text boxes will add the from => to mapping to the Animation File => Character text box. The Animation File => Character display is self correcting, so if you make a mistake and change the object mapping to the "Reference Character Controls" object, it will replace the map you previously entered with the updated one.

I've left all the manual buttons for conveying data in the interface like "Get Info from File" , "Get Character Controls" and "Map to New Character" even though I've added more automation for those features so they generally aren't necessary. If all the automated stuff continues to work under production use, then I might take the buttons out.

Reading mapped files is a "What you see is what you get" process, since the information is actually taken from the "Animation File => Character" text box, and not the variables used to create the box.

Making everything in these text boxes update automatically when options were changed turned out to be more challenging than I thought. It's still not perfect, and sometimes to get the "Character List" (at the top) to update with the proper amount of rows, I have to turn "Show Objects Selected With Wildcard" checkbox on and off.

Another challenge was getting a perfect match on tangents and weights on curves. It turned out that if the animation had options like "Weighted Tangents" or "Lock Tangent Weights" turned on or off, I'd get incorrect information in the saved file. It was solved by caching the current state of the tangents and weights, turning weighted tangents on, unlocking tangent weights, breaking the tangents, saving the information, and then turning them back on with the cached state. All of that information is saved unless the "Motion Capture" checkbox is checked, in which case no tangent information is saved (everything is assumed to be linear since there's a key on every frame), and no "infinity" information is saved ("infinity" is assumed to be constant).

I'm using my own file format rather than an existing one. It doesn't seem like there's a truly universal animation file format being used, and I can add to this one or subtract from it at will based on the needs of the production. I've already had to add additional variables for accurate tangent weight replication. Since the format easy to parse out, it can be translated to anything else that's ASCII based with pretty little effort, though the translation can be time consuming if a lot of recursion is needed. The downside is that the files can be huge, but they are "human readable".

The "Name" basis of this file format makes it particularly suited to production, since hierarchies can change during production, particularly the number of children of a particular hierarchy, which I've found throws things off a great deal and can make old animation incompatible with new animation. The remapping feature seems to be a pretty obvious need, and it's amazing that it's not something that's become a standard feature set in Maya.

I would really like to resolve a memory issue with using the animation file loader, particularly with motion capture files, which have a huge amount of data. During loading, it will suck up a ton of memory, even sending my machine into "swap" virtual memory space. And it doesn't give it back when the process is finished. The only solution I have right now is to save the scene, kill Maya and then restart Maya. If anyone has any solutions to this problem, I'd love to hear them.

Plans for the future:
The underlying code can be used for scene loading, bypassing the reference process in Maya if it becomes necessary, providing the code proves to be reliable enough and I resolve the annoying memory issues. If there's a use for it, I can use a "Save by timeline" feature, and maybe a "hide until first frame" feature for characters that have no animation until the middle of a shot.

I may also add an "animation copy" feature, to copy animation between two characters loaded at the same time, possibly deploying the techniques I'm using in another tool that turns hierarchical straight FK rotation keys into IK translational keys between dissimilarly proportioned characters.

If it can be made more efficient, I might make a multi-select reference mode that can load the same animation on multiple characters for crowd scenes, with a random range of time offset to the characters aren't all moving at the same time. I've thought of ways to also randomize initial character placement so the characters are at a fixed proximity to the other characters, but it would be hard to duplicate some of the features I've heard about in Massive. Also, I'd have to work on my use of matrices to determine location within a bound distance.