alphanumeric slot type
Create an AMAZON.ALPHANUMERIC slot type (although with a better, shorter name!) This would extend the current AMAZON.NUMBER slot type and hopefully improve the recognition model. Discussed in https://forums.developer.amazon.com/questions/4821/how-would-you-design-slots-for-letter-and-number-c.html
Dave Curley commented
Upvoted. In the meantime any time I've had to do this in a skill, I've used a custom slot type "alpha_char" which expects [0-9][A-Z]. For the [A-Z] each letter has its phonetic alphabet equivalent as a synonym (alpha, bravo, charlie, etc). This works well except for a single case of intent confirmaiton: if the input slot sequence has a digit adjacent to an 'N' and the customer says 'November' (the phonetic for N), intent confirmation doesn't work well. It interprets "3 November" or "November 3" as a date. There's no way for the skill to override this as the confirmation is upstream of the request being delivered. So only recourse is to disable confirmation and do that in the skill itself, which is messy. Something to keep in mind if this makes it to implementation.
John Campbell commented
This would be good for car reg. Would be be nice to have rules you can give e.g. number of values, which type and certain positions etc