ruler wiki says "A ruler is a flat piece of wood or metal, used for measuring short distances ..."

1) Some ruler posts don't show that kind of ruler.

1A) post #3292648 (tag as royalty ?)

(side-issue for that 3292648 post: i see only one character in art, but is tagged with 3 char tags:

• draken (character) ... 19
• draken sjacharytiss ... 19
• drakrothiken ... 7 )

( in FA folder titled "Draken Sjacharytiss - All Images of Draken"
https://www.furaffinity.net/gallery/lorddraken/folder/787275/All-Images-of-Draken/ )

1B) post #3205783 , no ruler shown.
changing to tag height_chart (wiki "where a character is placed in front of a chart to measure their height and/or when characters have their heights compared to one another.")

1C) changed some from ruler to tape_measure : example post #3089826

(https://en.wikipedia.org/wiki/Tape_measure )

2) there is also tag measuring_stick
which all seem to show a ruler (the measuring kind).

***

(Made is partway through first page of ruler:
from latest ( 3473920 .. warning: possibly cub???)
to post #2887395 (not sure if ruler tag is appropriate for this image ... already tagged with penis_size_chart )

(going offline to finish Parts and Rec before it leaves Netflix)