When creating your Alexa skill, it’s important that you represent all acronyms correctly. This applies not only to your invocation name, but also to the rest of your skill’s interaction model.
As outlined in the Invocation Name Requirements documentation, for any invocation name containing an acronym, periods and spaces should be used if the acronym is pronounced as a series of individual letters. For example, in the case of “NPR”, the letters should be all lowercase and separated by periods and spaces like this: “n. p. r.”. An exception is if the abbreviation is pronounced as a word, as in “NASA”. In this case it should be all lowercase but not contain periods or spaces like this: “nasa”.
Additionally, your invocation name cannot spell out phonemes. For example, a skill titled "AWS Facts" would need "AWS" represented as "a. w. s. " and NOT "ay double u ess."
Slot values are sent to your skill in written format. For example, both "fire h.d. 7" and "fire h.d. seven" would be sent to your skill as "Fire HD7". For better recognition, acronyms and other phrases involving spoken letters should either be all caps ("HD") or separated by periods and spaces ("h. d. ").
Using lowercase for initialisms may lead to unreliable recognition since the spoken form may not correctly be detected. Check out the Custom slot type values table for more examples of slot type values and how they are converted to written form when provided to your service.
As with your skill’s invocation name, acronyms in your sample utterances should be separated by periods and spaces (for example "n. b. a.", not "nba"). Take a look at Rules for Sample Utterances for additional information.