When writing code for the Atari 2600 I use the compiler dasm.
With dasm, the opcodes are case-insensitive so LDA can be written as LDA, lda, Lda, etc. As such, I've set the mode file to use <RULES IGNORE_CASE="TRUE">.
I've configured the mode file so the 2600's registers such as GRP0, which holds sprite0's shape for the current scanline*, get syntax highlighted. However, dasm is case-sensitive when it comes to variable names. As such, if I type grp0 into my source code the compile will fail.
As such, I'd like to be able to make some of the keywords case-sensitive even though most of them are not. Can this be done with jEdit? My current mode file, assembly-6502, can be found here. I'm planning to do an update soon and will be renaming it Atari 2600 Assembly as the mode file's not really for generic 6502 assembly language.
* Yep, just the current scanline. When the Atari 2600 was developed memory was extremely expensive, so much so that the 2600 only contains 128 bytes of RAM. So TIA, the video chip, was designed to be scanline based. This means the registers in TIA only contain enough information to draw a single scanline, so your code must update TIA's registers on each and every scanline in order to draw the screen the player sees.