There should be a new file format, that can be customized. For example, consider the volume of notes. In mptm file format, it's always in a scale out of 64. However you may want greater precision so you customize the file format to use a scale out of 256; the information about the file format customization is in header. Or the opposite; you may want to directly use fades like 16-12-9-7-5-4-3-2-1 (requires proper settings to seamlessly play consecutive notes) without multiplying the numbers by 4. Also, the custom file format should provide lots of flexibility, like allowing long pattern length (I don't like the idea of splitting songs). Oh, guess what? This custom file format can also have potential to provide a feature mptm doesn't: different time resolutions on different channels!

So, this custom file format simply should bypass limitations:

1. of always having volume out of 64; there may be an option to freely select a fractional value from scale out of 1, or an option of having volume scale out of different integers
2. of having only 1024 pattern length; people like me don't like the idea of splitting songs
3. of having equal time resolution on every channel
4. of only having 120 different pitches (finetuning doesn't fix the range problem)¹
   and some more you can think of.

¹For unusual type of tunings, like Hz-based (16, 32, 48, etc. Hz) or period (inverse Hz) based (8000, 4000, 2666.7, etc. Hz), you may run out of range quicker than octave based ones, also tunings like these have no generator built in so they are hard to create