That moment when you realize Thunderstorm is a single word. And yay no shard banned 
More then one word. "Shard of ______"
SoR, SoSe 
Unfortunately, n00b predicted that and said "no more than a capital letter.
Grammatically speaking you're suppose to write it like this: S.R. which would stand for shard (of) readiness. English acronym's make letters for only words that are above 3 letters long. Acronyms aren't considered words, but multiple words for each letter and each missing letter.
P.S. unappropritate you need 10 non-spam posts. This is one, go to the introduce yourself in general discussion for a 2nd, and then try "show unread posts since last visit" at the top of any page.