And you will not find any official Pushover documentation to that effect. When we created the original Pushover Driver for Hubitat, we had to come up with ways to utilize the features of the Pushover API, while staying within the constraints of the Hubitat Notification Standard Capability. Thus, we embedded features like the message priority with brackets, which the driver then strips off before making the proper Pushover API call.
You can read through the history of the Pushover community driver development by reading the following thread. The first post also explains the use of all of the features that have been implemented. Note: Some features require the use of the Community version of the driver, as the community has continued to add features even after Hubitat took their snapshot of the code to include in the Hubitat Platform.
