Percentage Sign handling in NAV is dangerously flaky

OBJECT Report 88888 Percentage Sign Trouble
{
  OBJECT-PROPERTIES
  {
    Date=28-10-11;
    Time=14:30:37;
    Version List=;
  }
  PROPERTIES
  {
    ProcessingOnly=Yes;
    OnPreReport=BEGIN
                  // Percentage Sign handling in NAV is dangerously flaky.

                  // For quite some time now I've been frustrated by the apparently inconsistent behaviour of STRSUBSTNO.
                  // Eventually I needed to get a grip on the shortcomings of this function. This is the result.

                  MESSAGE('%1',STRSUBSTNO('This should output 10%: %1%',10));  // This works.
                  MESSAGE('%1',STRSUBSTNO('This should output 10%: %1%2',10,'%'));  // So does this.
                  MESSAGE(STRSUBSTNO('This should output 10%: %1%',10));  // But this doesn't (it even puts the result on a separate line!)
                  MESSAGE(STRSUBSTNO('This should output 10%: %1%2',10,'%'));  // And neither does this  (also puts the result on a separate line)

                  // How about putting the message into a text variable before showing it?
                  String := STRSUBSTNO('This should output 10%: %1%',10);
                  MESSAGE('%1',String);  // This works.
                  MESSAGE(String);  // But this doesn't.

                  // This demonstrates that it is in fact not STRSUBSTNO that's the culprit. It's MESSAGE.
                  // Let's streamline the example:
                  MESSAGE('%1','This should output 10%: 10%');  // This works.
                  MESSAGE('This should output 10%: 10%');  // But this doesn't. Like, not at all.

                  // I've created a text constant with the same value as String below.
                  // In essence, you would expect all three messages to display the same. But they don't,
                  String := 'This should output 10%: 10%';
                  MESSAGE('This should output 10%: 10%');  // This doesn't work.
                  MESSAGE(String);  // But this does.
                  MESSAGE(TextConstant);  // And so does this.

                  // By now I guess my suggestion would be to always replace % with the text 'pct.'...

                  // But the percent sign is not nearly done creating havoc. It gets much worse:
                  MESSAGE(STRSUBSTNO('This should output X0X: %1%2%1','X',0));  // This works.
                  MESSAGE(STRSUBSTNO('This should output 909: %1%2%1','9',0));  // This doesn't.
                  MESSAGE(STRSUBSTNO('This should output 909: %1%2%1',9,0));  // And neither does this.

                  // You get even "funnier" results using this method:
                  MESSAGE('%1',STRSUBSTNO('This should output X0X: %1%2%1','X',0));  // This works.
                  MESSAGE('%1',STRSUBSTNO('This should output 909: %1%2%1','9',0));  // This fails spectacularly.
                  MESSAGE('%1',STRSUBSTNO('This should output 909: %1%2%1',9,0));  // So does this.

                  // The last two statements show that it doesn't matter if the number is an actual integer or a text.
                  // Too bad as this ensures you can't do a workaround using FORMAT.
                  // It also means that your code could be working perfectly for years until one of the parameters for one reason or another.
                  // is changed from a text to a number (say, a setup parameter defining a file path).

                  // So why haven't you bumped into this before? Well, that's when it gets seriously messed up:
                  MESSAGE('%1',STRSUBSTNO('This should output 909: %1%2%3',9,0,9));  // This works.
                  MESSAGE('%1',STRSUBSTNO('This should output 909: %1%2%1',9,0,9));  // While this fails.

                  // What this shows is that the ORDER of the % fields affects the result!
                  // In essence you should ALWAYS use parameters sequentially. Too bad if you using STRSUBSTNO to achieve something like this:
                  String := STRSUBSTNO('%1%4%2%4%3%4','field1','field2','field3',';'); // The semicolon represents a delimiter, e.g. for data export.
                  MESSAGE(String);  // This actually works! But why? Because none of the parameter values are numbers. Observe:
                  String := STRSUBSTNO('%1%4%2%4%3%4','field1','999','field3',';');
                  MESSAGE('%1',String);  // I was using this method to create a delimited file and I'm still seeking professional help.
                  MESSAGE(String);  // It's even better if you resort to debugging using MESSAGEs... Now one of the fields have vanished!}

                  // The error does not affect the first parameter. That would be too easy. The remaining ones do exert a horrible revenge, though:
                  String := STRSUBSTNO('%1%4%2%4%3%4','1','2','3',';');  // Expect "1;2;3;"
                  MESSAGE('%1',String);  // Not "1;2;3;". Not even close.
                  MESSAGE(String);  // Distance from the expected result is measured in light years for this one...

                  // Incidentially, did you ever try to to MESSAGE a file path but instead got a new line for each backslash?
                  // The MESSAGE('%1',... workaround handles this too:
                  MESSAGE('%1','C:\Program Files');  // This gives you the backslash.
                  MESSAGE('C:\Program Files');  // This gives you a new line.

                  // However, in this case it actually makes sense as it tells MESSAGE to either show the string "as is" or subject it to NAV's
                  // internal formatting routine. It's obviously the same logic that makes the % examples work with MESSAGE('%1',...
                  // But if you're unlucky you'll end up in a situation where you actually need both the "as is" result and the formatted result:
                  String := STRSUBSTNO('This should output 10% on a new line:\%1%',10);
                  MESSAGE('%1',String);  // This doesn't work (everything is on one line)
                  MESSAGE(String);  // Neither does this.

                  // The last example actually converts the first % to a new line for no apparent reason, resulting in a 3 line message...

                  // I'm not overwhelmingly impressed.
                END;

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    PROPERTIES
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      Width=9020;
      Height=3410;
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    CONTROLS
    {
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  CODE
  {
    VAR
      String@1000000000 : Text[1024];
      TextConstant@1000000001 : TextConst 'ENU=This should output 10%: 10%';

    BEGIN
    END.
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