@tony-- has encountered some cases where the identifier is too strict in its lowest common denominator approach. It would be nice if the valid-identifier package could return a valid identifier, which could be used.

More from Tony and team here :

Windows (Identity/Name)
The name is an attribute of the Identity element in the application manifest file.
Must consist of of between 3-50 characters.
The identity/Name must contain only letters, numbers, the “-“, and the “.”.
Cannot end in a period.
The Identity/Name cannot be:
“CON"
"PRN"
"AUX"
"NULL"
“COM1” - “COM9"
“LPT1” - “LPT9"
Link: https://msdn.microsoft.com/en-us/library/windows/apps/dn423277.aspx (window 8.1)
Windows (Application/Id)
This field is updated with the text put into the Identity/Name field by Cordova. These fields have conflicting specifications so I have listed it here. I have hi-lighted the potentially conflicting requirements.
The Application/Id name in the application manifest file.
Must consist of between 1-64 characters
The Application/Id must contain only letters, numbers, and the “.”.
Each section must begin with an ASCII alphabetic character.
The Identity/Name cannot be:
“CON"
"PRN"
"AUX"
"NULL"
“COM1” - “COM9"
“LPT1” - “LPT9"

iOS (Bundle Id)
Is the BundleId of the application plist file.
Is a Uniform Type Identifier (UTI)
Contain at least two sections. Sections are separated by the period character “.”.
The bundle id must only contain letters, numbers, the “_”, “-“, and the “."
Should be organized in the reverse-DNS format.
Cannot end in a period.
Link: https://developer.apple.com/library/prerelease/watchos/documentation/IDEs/Conceptual/AppDistributionGuide/ConfiguringYourApp/ConfiguringYourApp.html#//apple_ref/doc/uid/TP40012582-CH28-SW2

Android (Package Name)
Is a name in the AndroidManifest.xml file.
Must have at least two sections. Sections are separated by the period character “.”.
Each section must have at least one character.
The first character must be lower case.
Each section must not start with a number
Each section must not be a Java keyword
Each section cannot start with the word “java”.
The package name must only contain letters, numbers, the “_”, and the “."
Cannot end in a period.
Android Link: http://developer.android.com/guide/topics/manifest/manifest-element.html#package
Java Link: https://docs.oracle.com/javase/specs/jls/se7/html/jls-6.html#jls-6.1 (java 7)

Hello,

I am curious why 'decimal' is considered a banned key word I seem to be able to create App id's with it in the identifier for Xcode, Android Studio, VisualStudio and Appcelerator Titanium.

What is blocking here and what can I do to help?

It does not contain await or enum for example.