Joe F:

I expect that probably everyone can. But that doesn't necessarily make it a good choice to document tunes on a web site. For example, leeneia indicated that she can sing (so it's likely in the extreme that she can sing the scale). She said that she can't find any OTHER intervals than the scale degrees, in order.

Joe Offer asked how you can use it to indicate rhythm, upper octave, and lower octave. I can imagine several possibilities. But there is no standard way of doing so.

I want to know how you indicate accidentals. I seem to recall that you add -a or -i to the first letter to make sharps or flats, but I don't remember which. Again, there's not really a standard way of doing so.

Finally, much of Europe uses a "fixed do". That is, "do" literally means "C". Meanwhile, the States (and the UK?) uses a "relative do". IOW, "do" means the root of whichever key the song is in. Which way should MudCat use?

No, "do re me" simply has not even a vague hint of a standard. Without one, it is not a suitable method for indicating the tune on a site that is consulted by people around the world.

ABC is a recognized standard. If you can read Western music notation, you can learn to read ABC very quickly. I've been using it long enough that I can read it as quickly and easily as I read music. I literally make notes on tunes in ABC live, faster than I can write dots. For those who cannot read notation, there are plenty of online or downloadable tools to play ABC melodies and/or to display ABC in notation. ABC even has the capacity for harmony built into it.

For details, see https://abcnotation.com.

BB,
NightWing