We have been asked whether there is any difference between the two types of quotes that can be used by Ax. The answer is very simple: X++ makes absolutely no distinction between the two. The reason that there are two quote characters is to facilitate constructs themselves containing quote characters, like

str s = ‘<MyTag attr="hello">’;

Writing this with only one quote character would be difficult to read because escape characters would have to be used to distinguish the quotes defining the extent of the string from those that occur in the string, as

str s = "<MyTag attr=\"hello\">";

That said, the application community has best practices that mandate that programmers use '(single quotes) for text that cannot appear on UI, like

System.Int32 myVar = CLRInterop::CLRNull('System.Int32');

Whilst text that does should use double quotes for text like

myButton.Label = "@SYS12345";