Open Firmware syntax lets you encode arbitrary bytes as hex pairs in a string literal. It's used when the literal is a binary blob rather than text, and you don't want to be limited to just printable characters in your string.
" "(xxxx)"
Here's a breakdown of the code, annotated with what the stack looks like at the end of each line.
" "(xxxx)" ( str-base str-len)
dup -rot ( str-len str-base str-len)
alloc-mem ( str-len str-base mem-base)
dup 2swap ( mem-base mem-base str-len str-base)
-rot ( mem-base str-len str-base mem-base str-len)
move ( mem-base)
1 byte-load ( )
So the NVRAM script takes a hex string, copies it into memory, and then uses byte-load to run it as a FCode script. The memory isn't freed afterwards, which isn't that big a deal for OF.
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
So what does the FCode script do? I have no idea. To figure it out, we will have to detokenize it into Forth source code. While you certainly can go to section "G.2 Assigned FCode numbers" of the "IEEE Standard for Boot (Initialization Configuration) Firmware: Core Requirements and Practices" pdf and manually decode each byte, I do not recommend it. Instead, compile and run the tool at this url.
https://github.com/openbios/fcode-utils/tree/master/detok. It will do most of the work for you.
You will probably have to convert the hex pairs into raw bytes in a file before the tool can use it. Google suggests the following command, though I havn't tested it myself.
xxd -r -p input.hex output.bin
Good luck, have fun.