[loeg]

To be a little pedantic, the usual zstd levels are positive integers (1-22 default 3). The negative integers denote "fast" modes with worse compression (there are only a few of these).

[edflsafoiewq]

I think those are CLI options, not negative signs. Ie. you call zstd -3 for compression level 3.

[a_t48]

Whoops! You're right, and it's too late to edit.