If you are developing an extension, then please follow the naming conventions, which is UpperCamelCase for property, method and event names (i.e. the first letter should be a capital letter) and lowerCamelCase for parameter names, no underscores .
All components and extensions follow the naming conventions… and these naming conventions have been setup by the MIT App Inventor team, see also the App Inventor Extensions document
see here why naming conventions make sense
Why are naming conventions important programming?
Naming conventions help your code stay fluent within the context of your program . This is important because you want to have consistency throughout your entire program . Below you will find general rules when naming your variables. Variables tend to start with a letter.
Feel free to use your own naming conventions in your own project, but if you like to provide an extension for others, then please follow the already defined naming conventions to make life easier for everyone.