diff --git a/sh/argc b/sh/argc
index 96b5c87..c528f9e 100755
--- a/sh/argc
+++ b/sh/argc
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 argc() { ### @- validate the number of arguments in a function.
     ### ```sh
diff --git a/sh/arith b/sh/arith
index 9a930a7..77bf4eb 100755
--- a/sh/arith
+++ b/sh/arith
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # though technically compatible with other shells,
 # extra functionality is through zsh's extended arithmetic functions.
diff --git a/sh/arrays b/sh/arrays
index c71c311..6d8e7e3 100644
--- a/sh/arrays
+++ b/sh/arrays
@@ -1,5 +1,5 @@
 #!/usr/bin/env false
-# YES_ZSH YES_BASH NO_DASH NO_ASH
+# compat: -ash +bash -dash +zsh
 
 whoa=(
     -Wall
diff --git a/sh/askey b/sh/askey
index 153cff8..e7bc849 100755
--- a/sh/askey
+++ b/sh/askey
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 askey() {
     printf '\033[100m 00 \033[m \033[100m 01 \033[m \033[100m 02 \033[m \033[100m 03 \033[m \033[100m 04 \033[m \033[100m 05 \033[m \033[100m 06 \033[m \033[100m 07 \033[m \033[100m 08 \033[m \033[100m 09 \033[m \033[100m 0A \033[m \033[100m 0B \033[m \033[100m 0C \033[m \033[100m 0D \033[m \033[100m 0E \033[m \033[100m 0F \033[m
diff --git a/sh/autosync b/sh/autosync
index 81e806a..d4996bf 100755
--- a/sh/autosync
+++ b/sh/autosync
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 # TODO: portable way of dodging aliases to allow other shell support?
 
diff --git a/sh/bak b/sh/bak
index 3d79fe6..6b971f1 100755
--- a/sh/bak
+++ b/sh/bak
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 bak() { ### @-
     ### backup files by creating copies and appending ".bak" to their names.
diff --git a/sh/baknow b/sh/baknow
index 9991615..ac1e451 100755
--- a/sh/baknow
+++ b/sh/baknow
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 baknow() { ### @- backup files by appending their timestamps given by [`now`.](#now)
     ### ```
diff --git a/sh/baks b/sh/baks
index bfacea9..d428d44 100755
--- a/sh/baks
+++ b/sh/baks
@@ -1,6 +1,6 @@
 #!/usr/bin/env sh
 # backup, timestamped
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 baks() { ### @-
     ### backup files by copying each and appending *the current* date-time,
diff --git a/sh/bin b/sh/bin
index 169b951..2cdaf1c 100755
--- a/sh/bin
+++ b/sh/bin
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # though technically compatible with other shells,
 # extra functionality is through zsh's extended arithmetic functions.
diff --git a/sh/burl b/sh/burl
index 66c2469..c67b8b0 100755
--- a/sh/burl
+++ b/sh/burl
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 burl() ( ### @-
     ### turn bash into a makeshift HTTP client.
diff --git a/sh/busiest b/sh/busiest
index 131185a..b230e79 100755
--- a/sh/busiest
+++ b/sh/busiest
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 busiest() { ### @-
     ### list directories in descending order by the number of files in them,
diff --git a/sh/clash b/sh/clash
index 57c46a5..46d50a0 100755
--- a/sh/clash
+++ b/sh/clash
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 clash() { ### @- run a command through 12 different shells.
     ### only returns false when no arguments are given.
diff --git a/sh/colors b/sh/colors
index 28b44a6..e979bc6 100755
--- a/sh/colors
+++ b/sh/colors
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# YES_ZSH YES_BASH NO_DASH NO_ASH
+# compat: -ash +bash -dash +zsh
 
 colors() { ### @-
     ### display all combinations of foreground and background terminal colors.
diff --git a/sh/colors2 b/sh/colors2
index 3a0b262..7a9e9e4 100755
--- a/sh/colors2
+++ b/sh/colors2
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 colors2() {
     [ $# -eq 0 ] || { printf "%s\n" "$0: does not take arguments" >&2; return 1; }
diff --git a/sh/compile b/sh/compile
index 37976b1..775b542 100755
--- a/sh/compile
+++ b/sh/compile
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 setup_clang_ubuntu() { ### @-
     ### print (but don't execute) the commands necessary to install
diff --git a/sh/confirm b/sh/confirm
index 6915823..56de0c7 100755
--- a/sh/confirm
+++ b/sh/confirm
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 ### @ confirm
 ### display a simple yes-or-no prompt and return 0-or-1 respectively.
diff --git a/sh/countdiff b/sh/countdiff
index 04e8418..0dbdc06 100755
--- a/sh/countdiff
+++ b/sh/countdiff
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK YES_OT_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK YES_OT_AWK
 
 countdiff() { ### @-
     ### count the number of lines changed between two files.
diff --git a/sh/cutv b/sh/cutv
index 388c60c..0f5c44a 100755
--- a/sh/cutv
+++ b/sh/cutv
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 cutv() {
     argc $# -ge 2 "$0" || return
diff --git a/sh/dated b/sh/dated
index 350c6f5..afab5d5 100755
--- a/sh/dated
+++ b/sh/dated
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 dated() {
     local ts= u=0
diff --git a/sh/days b/sh/days
index 1dc31a5..18ada23 100755
--- a/sh/days
+++ b/sh/days
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 days() { ### @-
     ### compute the number of days since a given date.
diff --git a/sh/decently b/sh/decently
index d95527c..389101a 100755
--- a/sh/decently
+++ b/sh/decently
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # TODO: check if this is compatible with busybox.
 
diff --git a/sh/dedupe b/sh/dedupe
index 78ade4f..a4e344d 100755
--- a/sh/dedupe
+++ b/sh/dedupe
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 dedupe() ( ### @- copy a directory, but make hard/softlinks for identical files.
 # Copyright (C) 2022 Connor Olding
diff --git a/sh/dfu b/sh/dfu
index e6465dd..7828125 100755
--- a/sh/dfu
+++ b/sh/dfu
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK YES_OT_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK YES_OT_AWK
 
 dfu() { ### @-
     ### pretty-print `df` in GiB.
diff --git a/sh/disowned b/sh/disowned
index 0d6cd00..16b1fe6 100755
--- a/sh/disowned
+++ b/sh/disowned
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 disowned() { ### @- find files in system directories that aren't associated with any pacman packages.
     #
diff --git a/sh/e b/sh/e
index 671fc9c..fe84284 100755
--- a/sh/e
+++ b/sh/e
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK
 
 e() { ### @-
     ### wrap around `$EDITOR` to run it as root if necessary.
diff --git a/sh/ea b/sh/ea
index 4a9cfd5..ac582e3 100755
--- a/sh/ea
+++ b/sh/ea
@@ -1,6 +1,6 @@
 #!/usr/bin/env sh
 # remote file access (http file-sharing shenanigans)
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __ea_curl() {
     curl -q --no-progress-meter 127.255.255.255 >/dev/null 2>&1
diff --git a/sh/echo2 b/sh/echo2
index d705944..5dd7a12 100755
--- a/sh/echo2
+++ b/sh/echo2
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 echo2() { ### @-
     ### print arguments joined by spaces to stderr without parsing anything.
diff --git a/sh/explore b/sh/explore
index 5801dd4..8175647 100755
--- a/sh/explore
+++ b/sh/explore
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 explore() { ### @- open a single directory in `explorer.exe`, defaulting to `$PWD`.
     [ -n "$MSYSTEM" ] || { printf "%s\n" "$0: only for MSYS2" >&2; return 1; }
diff --git a/sh/feud b/sh/feud
index ffdfdd9..c2d70b8 100755
--- a/sh/feud
+++ b/sh/feud
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 ### @feud - parse command-line arguments, mapping short-flags to variable names.
 ### **NOTE:** the API is still experimental and will undergo major changes.
diff --git a/sh/ff b/sh/ff
index efef09c..5086410 100755
--- a/sh/ff
+++ b/sh/ff
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 ff() { ### @-
     ### select a file from a given or current directory using
diff --git a/sh/ghmd b/sh/ghmd
index d895358..dc2bcbb 100755
--- a/sh/ghmd
+++ b/sh/ghmd
@@ -2,7 +2,7 @@
 # ghmd - format GitHub markdown
 # via: https://leahneukirchen.org/dotfiles/.zshrc
 # example: ghmd < README.md > README.html
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 ghmd() { ### @-
     ### convert a markdown file to HTML in the style of GitHub.
diff --git a/sh/glug b/sh/glug
index f60a635..2a59c69 100755
--- a/sh/glug
+++ b/sh/glug
@@ -1,5 +1,5 @@
 #!/usr/bin/env dash
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 # fuck termcap, all my homies hate termcap.
 
 glug() ( # note the subshell syntax. this allows us to abuse globals like crazy.
diff --git a/sh/grab b/sh/grab
index 20a81c7..12b644e 100755
--- a/sh/grab
+++ b/sh/grab
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __grab() { ### @grab - download a file from my site and verify its integrity by its [minisign](https://github.com/jedisct1/minisign/) signature.
 [ -z "${ZSH_VERSION}" ] || emulate sh
diff --git a/sh/grop b/sh/grop
index e1c0bd6..0392b7c 100755
--- a/sh/grop
+++ b/sh/grop
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # TODO: check for existence of grep -P; write a perl-based fallback.
 grop() { ### @- invoke grep with `-oP`.
diff --git a/sh/grop4 b/sh/grop4
index 756abe7..478c7ee 100755
--- a/sh/grop4
+++ b/sh/grop4
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 grop4() { ### @- [`grop`](#grop) for IPv4s.
     grep -oP -- '(?<=^|[^\d.])((0|1\d\d|2[0-4]\d|25[0-5]|[1-9]\d?)\.((?2))\.((?2))\.((?2)))(?=$|[^\d.])'
diff --git a/sh/has b/sh/has
index ffa3c51..c9ec9ae 100755
--- a/sh/has
+++ b/sh/has
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 has() { ### @- [`have`,](#have) silently.
     if [ -z "$ZSH_VERSION" ]; then which -- "$1"; else whence -p -- "$1"; fi
diff --git a/sh/have b/sh/have
index 45e3690..d3d9d9f 100755
--- a/sh/have
+++ b/sh/have
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 have() { ### @- print the result of `which` if the program is found, else simply return 1.
     ### ```
diff --git a/sh/hex b/sh/hex
index 2e4c8b3..0ba6b4f 100755
--- a/sh/hex
+++ b/sh/hex
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # though technically compatible with other shells,
 # extra functionality is through zsh's extended arithmetic functions.
diff --git a/sh/ify b/sh/ify
index 83307a6..d3982b7 100755
--- a/sh/ify
+++ b/sh/ify
@@ -1,5 +1,5 @@
 #!/usr/bin/sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 ify() { ### @-
     ### pipe one command through another, so you can still pass arguments to the former.
diff --git a/sh/is_empty b/sh/is_empty
index 3b41a3c..5b8dde3 100755
--- a/sh/is_empty
+++ b/sh/is_empty
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# YES_ZSH YES_BASH NO_DASH NO_ASH
+# compat: -ash +bash -dash +zsh
 
 is_empty() { ### @-
     ### return 0 if the directory given by argument is empty.
diff --git a/sh/isup b/sh/isup
index 0122bc6..0fd2789 100755
--- a/sh/isup
+++ b/sh/isup
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 isup() { ### @-
     ### return 0 if a given website returns a 2xx HTTP code.
diff --git a/sh/join2 b/sh/join2
index 3ac8743..c29ba3a 100755
--- a/sh/join2
+++ b/sh/join2
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 join2() { ### @- join every other line.
     # TODO: argc, also better interface that allows n file inputs without stdin.
diff --git a/sh/lsarchive b/sh/lsarchive
index dfa54c0..5fdbfc9 100755
--- a/sh/lsarchive
+++ b/sh/lsarchive
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 lsarchive() { ### @- list the contents of an archive file in one of many formats.
     ### borrowed from [prezto.](https://github.com/sorin-ionescu/prezto)
diff --git a/sh/maybesudo b/sh/maybesudo
index c592891..c4953eb 100755
--- a/sh/maybesudo
+++ b/sh/maybesudo
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __maybesudo() { ### @maybesudo
     ### mimic certain features of `sudo` for systems without it installed.
diff --git a/sh/minutemaid b/sh/minutemaid
index 27f4243..df31c20 100755
--- a/sh/minutemaid
+++ b/sh/minutemaid
@@ -1,5 +1,5 @@
 #!/usr/bin/env dash
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 minutemaid() { ### @-
     ### check if the current minute is divisible by a given number,
diff --git a/sh/monitor b/sh/monitor
index 715cc93..a553951 100755
--- a/sh/monitor
+++ b/sh/monitor
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 monitor() { ### @-
     ### this is [watch(1)](https://www.man7.org/linux/man-pages/man1/watch.1.html)
diff --git a/sh/morecolors b/sh/morecolors
index 46acc0a..9948e07 100755
--- a/sh/morecolors
+++ b/sh/morecolors
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# YES_ZSH YES_BASH NO_DASH NO_ASH
+# compat: -ash +bash -dash +zsh
 
 morecolors() { ### @- print all 256 colors that are available on most terminals.
     # borrowed from leah2's dotfiles.
diff --git a/sh/noccom b/sh/noccom
index 859e5da..0d3779b 100755
--- a/sh/noccom
+++ b/sh/noccom
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # TODO: what's the minimum version of perl required for this?
 
diff --git a/sh/note b/sh/note
index 0d514a3..644f47d 100755
--- a/sh/note
+++ b/sh/note
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 note() { ### @-
     ### act like [`echo2`,](#echo2) but use a bright color to stand out more.
diff --git a/sh/notice b/sh/notice
index f46faa4..6fb3dd6 100755
--- a/sh/notice
+++ b/sh/notice
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __notice_warn() {
 	printf >&2 'notice: %s\n' "$*"
diff --git a/sh/now b/sh/now
index 3647556..1c8a1d6 100755
--- a/sh/now
+++ b/sh/now
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 now() { ### @-
     ### print a date-time (UTC) in a sortable format.
diff --git a/sh/oshi b/sh/oshi
index 5a3daed..70dc62d 100755
--- a/sh/oshi
+++ b/sh/oshi
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __oshi() { ### @oshi
     ### upload files (or stdin) to [oshi.at.](https://oshi.at)
diff --git a/sh/oxo b/sh/oxo
index 797c8be..f55d466 100755
--- a/sh/oxo
+++ b/sh/oxo
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # **TL;DR RULES:**
 # * no executables (for the most part)
diff --git a/sh/pacbm b/sh/pacbm
index 8eba7b9..d0990c4 100755
--- a/sh/pacbm
+++ b/sh/pacbm
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # TODO: does this work with busybox awk?
 
diff --git a/sh/pause b/sh/pause
index 7f79cec..5587405 100755
--- a/sh/pause
+++ b/sh/pause
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 ### @ pause
 ### pause — the companion script of [`confirm`.](#confirm)
diff --git a/sh/pegg b/sh/pegg
index 41019ca..2d04b98 100755
--- a/sh/pegg
+++ b/sh/pegg
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 pegg() { ### @-
     ### download and (pip) install a Python "egg" from a project on GitHub,
diff --git a/sh/permit b/sh/permit
index 041c5b4..979a016 100755
--- a/sh/permit
+++ b/sh/permit
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __permit_hex() {
     if xxd -l 0 2>/dev/null; then
diff --git a/sh/pippy b/sh/pippy
index b2acd40..2b0d29c 100755
--- a/sh/pippy
+++ b/sh/pippy
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 pippy() { ### @-
     ### install Python packages using pip,
diff --git a/sh/pre b/sh/pre
index 2ca1dd9..fb425ad 100755
--- a/sh/pre
+++ b/sh/pre
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 pre() { ### @-
     ### dump all the `#define`s that `$CC $CPPFLAGS $CFLAGS $LDFLAGS` would result in.
diff --git a/sh/psbm b/sh/psbm
index b478169..5ef8969 100755
--- a/sh/psbm
+++ b/sh/psbm
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK
 
 psbm() { ### @-
     ### display and order processes by their memory usage ascending, and their sum.
diff --git a/sh/randir b/sh/randir
index eaf483c..95683b2 100755
--- a/sh/randir
+++ b/sh/randir
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # works with busybox.
 
diff --git a/sh/recolor b/sh/recolor
index b2cd5ad..fe1ff0b 100755
--- a/sh/recolor
+++ b/sh/recolor
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __recolor_install() {
     ForegroundColour() { recolor RAW 10 "$@"; }
diff --git a/sh/rot13 b/sh/rot13
index 84b968a..613b814 100755
--- a/sh/rot13
+++ b/sh/rot13
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # works with busybox tr.
 
diff --git a/sh/rs b/sh/rs
index 25efb21..103b960 100755
--- a/sh/rs
+++ b/sh/rs
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 rs() { ### @-
     ### record screen. does not record audio.
diff --git a/sh/running b/sh/running
index 5201ecf..3d6f3a2 100755
--- a/sh/running
+++ b/sh/running
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK
 
 # probably not compatible with busybox ps because its column 2 isn't PID.
 
diff --git a/sh/scount b/sh/scount
index 83c1a4f..2357d53 100755
--- a/sh/scount
+++ b/sh/scount
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 ### @ scount
 ### perform `sort | uniq -c | sort -n`, preferring GNU awk when available.
diff --git a/sh/scramble b/sh/scramble
index a613880..3b487ec 100755
--- a/sh/scramble
+++ b/sh/scramble
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # does not work with busybox sed (yet?)
 
diff --git a/sh/scropt b/sh/scropt
index b147fe2..474e506 100755
--- a/sh/scropt
+++ b/sh/scropt
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 scropt() { ### @-
     ### run `scrot` through `optipng` and save the result to `~/play/$(now).png`.
diff --git a/sh/shcom b/sh/shcom
index 0e74e44..1260f28 100755
--- a/sh/shcom
+++ b/sh/shcom
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 shcom() { ### @-
     ### comment out text from stdin and wrap it in a markdown blockquote
diff --git a/sh/similar b/sh/similar
index 22dcaa7..eacc481 100755
--- a/sh/similar
+++ b/sh/similar
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK
 
 similar() { ### @-
     ### highlight adjacent lines up to the first inequivalent character.
diff --git a/sh/slit b/sh/slit
index 86c59b9..abc9d1b 100755
--- a/sh/slit
+++ b/sh/slit
@@ -1,5 +1,5 @@
 #!/usr/bin/env dash
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # works with busybox ash.
 
diff --git a/sh/slitt b/sh/slitt
index abb4862..381437e 100755
--- a/sh/slitt
+++ b/sh/slitt
@@ -1,5 +1,5 @@
 #!/usr/bin/env dash
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 # works with busybox ash.
 
diff --git a/sh/sortip b/sh/sortip
index 28708cd..c1130ca 100755
--- a/sh/sortip
+++ b/sh/sortip
@@ -1,5 +1,5 @@
 #!/usr/bin/sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 sortip() { ### @- sort lines numerically by IPv4 segments.
     sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n "$@"
diff --git a/sh/sram b/sh/sram
index 4640f8c..72b9a3d 100755
--- a/sh/sram
+++ b/sh/sram
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH YES_BASH NO_DASH NO_ASH
+# compat: -ash +bash -dash +zsh
 
 sram() { ### @-
     ### convert between a couple saveram formats for N64 emulators.
diff --git a/sh/stfu b/sh/stfu
index 5fca20c..0a8abc7 100755
--- a/sh/stfu
+++ b/sh/stfu
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 stfu() { ### @-
     ### invoke a command, silencing stdout and stderr *unless* the command fails.
diff --git a/sh/streamcrap b/sh/streamcrap
index b1898e9..ba6396f 100644
--- a/sh/streamcrap
+++ b/sh/streamcrap
@@ -1,6 +1,6 @@
 #!/usr/bin/env false
 # awful things
-# YES_ZSH YES_BASH NO_DASH NO_ASH
+# compat: -ash +bash -dash +zsh
 
 mpvs() {
     mpv --quiet \
diff --git a/sh/subdue b/sh/subdue
index 1d1d608..94031ac 100755
--- a/sh/subdue
+++ b/sh/subdue
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 __subdue() { ### @subdue
     ### reconfigure your terminal's color scheme using a preset for [recolor.](#recolor)
diff --git a/sh/sum b/sh/sum
index 2fe77ff..522ecd2 100755
--- a/sh/sum
+++ b/sh/sum
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 sum() { ### @-
     ### compute the summation of its arguments without forking processes.
diff --git a/sh/sv b/sh/sv
index 94f5d5a..44ef5c9 100755
--- a/sh/sv
+++ b/sh/sv
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK
 
 sv() { ### @-
     ### collect the lastmost value of every key.
diff --git a/sh/trash b/sh/trash
index d7994b7..ae73451 100755
--- a/sh/trash
+++ b/sh/trash
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 trash() { ### @-
     ### output a given number of bytes from `/dev/random`.
diff --git a/sh/trunc b/sh/trunc
index 0930f2e..8105bc1 100755
--- a/sh/trunc
+++ b/sh/trunc
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK
 
 trunc() { ### @-
     ### truncate text to fit within your terminal using the unicode character `…`.
diff --git a/sh/unarchive b/sh/unarchive
index 288a964..f58d5a0 100755
--- a/sh/unarchive
+++ b/sh/unarchive
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 unarchive() { ### @- extract the contents of an archive file in one of many formats.
     ### borrowed from [prezto.](https://github.com/sorin-ionescu/prezto)
diff --git a/sh/unwrap b/sh/unwrap
index 23422a2..a9ab553 100755
--- a/sh/unwrap
+++ b/sh/unwrap
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 unwrap() { ### @- join paragraphs into one line each.
     awk '\''BEGIN{RS="\n\n";FS="\n"}{for(i=1;i<=NF;i++)printf "%s ",$i;print "\n"}'\'
diff --git a/sh/v_domap b/sh/v_domap
index d52fe42..227948a 100644
--- a/sh/v_domap
+++ b/sh/v_domap
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 v_domap() {
     argc $# -eq 1 "$0" || return
diff --git a/sh/v_lower b/sh/v_lower
index f5ddbf9..0479f99 100644
--- a/sh/v_lower
+++ b/sh/v_lower
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 v_lower() { ### @- transform the contents of a variable to lowercase.
     argc $# -eq 1 "$0" || return
diff --git a/sh/v_upper b/sh/v_upper
index 0a889ab..d787215 100644
--- a/sh/v_upper
+++ b/sh/v_upper
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 v_upper() { ### @- transform the contents of a variable to uppercase.
     argc $# -eq 1 "$0" || return
diff --git a/sh/wat b/sh/wat
index d386805..bfae5d3 100755
--- a/sh/wat
+++ b/sh/wat
@@ -1,5 +1,5 @@
 #!/usr/bin/env zsh
-# YES_ZSH NO_BASH NO_DASH NO_ASH
+# compat: -ash -bash -dash +zsh
 
 # wat - a better and recursive which/whence
 # via: https://leahneukirchen.org/dotfiles/tools.html
diff --git a/sh/wipe b/sh/wipe
index c414cd5..e6a3913 100755
--- a/sh/wipe
+++ b/sh/wipe
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH YES_BB_AWK
+# compat: +ash +bash +dash +zsh YES_BB_AWK
 
 wipe() { ### @-
     ### clear the screen and its scrollback, then print a high-contrast horizontal line.
diff --git a/sh/xxp b/sh/xxp
index 06e082a..cea9b5b 100755
--- a/sh/xxp
+++ b/sh/xxp
@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
-# YES_ZSH YES_BASH YES_DASH YES_ASH
+# compat: +ash +bash +dash +zsh
 
 xxp() { ### @-
     ### act like `xxd -p`, but nicely formatted.