On a recent episode of the Planetary Radio podcast, the topic of Third-Order Acronyms was brought up. At NASA, there are many Second-order acronyms like SAFER - Simplified Aid For EVA Rescue, where there is an acronym inside of an acronym. Are there any acronyms inside of acronyms inside of acronyms (Third Order) used in space exploration?
EDIT: Initialisms are also accepted.
"GIMP Is Mainly Photoshop"
returns exactly one result: your comment. $\endgroup$It's time [to] explain the meaning of "Hurd". "Hurd" stands for "Hird of Unix-Replacing Daemons". And, then, "Hird" stands for "Hurd of Interfaces Representing Depth". We have here, to my knowledge, the first software to be named by a pair of mutually recursive acronyms.
See here. $\endgroup$