I posted yesterday that 'NCLT' (now colloquially known as NIFC) was what the US Gov't called special edition currency; I read that once late '60's / early '70's in a coin rag... ... although the article might only have been a quote from one of Breen's Coin Encyclopedias, for he's the only reference I can find now - I don't see the acronym on pages for US Mint or BEP??? Any know anything else on it???
I didn't think it was an "official" term... more of a colloquial expression "coined" (pun intended) within our hobby
NCLT (Non Circulating Legal Tender) was used in the world coin collecting community for a few decades. When the US mint started making non proof coins and making them only for sale to collectors US collectors started calling these coins Not Intended For Circulation (NIFC). The first of these was the 1970 D half, then the 1973 Ike dollars, but the term NIFC didn't gain popular usage until after 2002 when the half dollars and Sac dollars all became NIFC. I can use either one but I used NCLT for years, long before NIFC came along, and I prefer that term.