Directive block - Gen<Directive:{custom;SingleLine;Unrestricted}> - 19 - (0:0,0)
    Transition span - Gen<None> - [@] - SpanEditHandler;Accepts:None - (0:0,0) - Tokens:1
        SyntaxKind.Transition;[@];
    MetaCode span - Gen<None> - [custom] - SpanEditHandler;Accepts:None - (1:0,1) - Tokens:1
        SyntaxKind.Identifier;[custom];
    Code span - Gen<None> - [ ] - SpanEditHandler;Accepts:Whitespace - (7:0,7) - Tokens:1
        SyntaxKind.Whitespace;[ ];
    Code span - Gen<DirectiveToken {;Member;Opt:False}> - [Some_Member] - DirectiveTokenEditHandler;Accepts:NonWhitespace - (8:0,8) - Tokens:1
        SyntaxKind.Identifier;[Some_Member];
