With ASCII sort ordering, upper case alphabets actually comes before the underscore (https://en.wikipedia.org/wiki/ASCII). The problem here (in native tree view) is that we sort them by the note's title which is always capitalized when created, but display them in the tree view with the file's URI, which will be not capitalized unless you named it with uppercase alphabets. In the web based tree view you can see that we are correctly displaying the capitalized note title (

A

). So if you want to have

_b.md

come before

a.md

, you would need to fix the frontmatter

title

property of the note

a.md

to be lowercase. Along with other related sort ordering issues, we will be changing the native tree view to correctly display the title instead of the file name to make it less confusing. Sorry about the inconvenience 🙏🏻 Note that with the upcoming fix, you will be able to set a custom frontmatter property

nav_order

to arbitrarily sort the notes in your tree view, so you may not need to add the underscore if the only reason for it was to bubble it up in the tree view.