Thanks Jim and Tony for answering my query.
In this day and age of texting and shortening our language, I had not come across this, but it is good to know. My grandchildren email me using 'text-type' (which I hasten to say I do not always understand at times either) but I've never seen this in their mail, so now I will be able to use it when replying to them. They'll either think I am 'cool' or a silly old ***** no prizes for guessing which. ha! ha!