Where to get a COMPLETE list of FIT profile and message definitions?

this is related to FIT decoding so I will post it here to help the next person

I have been frustrated that Garmin refuses to help 3rd party makers append info to FIT file summary, etc. via datafields 

So Stryd for example cannot write things like the user's running critical power (CP) and it's not supported natively from the stryd pod by Garmin as a sensor field like bike watts would be (FTP vs CP)

To workaround that apparently Stryd has a simple open web API to query any Stryd user by username

tiny bit alarming as it exposes info that might be considered semi-private but Garmin kinda forced this problem

(to be fair Stryd could have secured this with a password-like token also entered with the username into the datafield settings)

BUT this query will return "traininginfo.json" when you replace $1$ with the Stryd powercenter username

https:// www. stryd. com/b/user/$1$/watch/traininginfo

I've purposed broken the URL by putting spaces in there which you have to remove obviously