[v8i C#] Standards Checker string array parameters

Hey,

I try to implement IStandardsChecker via C#. All seems to work so far, but... when I try to use

void ShowCheckerErrorWithFixOptions(
  ref MsdStandardsCheckerReplaceChoice HandlingChoice,
  ref int SelectedFix, string ProblemDescription,
  string FixesListBoxLabel,
  ref string[] FixesColumnLabels,
  ref string[] Fixes,
  int DefaultFix,
  MsdStandardsCheckerReplaceOptions ReplaceOptions,
  bool CurrentlyIgnored,
  string IgnoredBy = null,
  DateTime IgnoredWhen = default(DateTime)
);

I get a "Value does not fall within the expected range." exception. I assume that it has something to do with ref string[] fixes.
In C# it should be string[], but VBA documentation says, it should be an array with 2 columns. But when I try to use

var fixes = new string[][] {...}

or

var fixes = new string[ , ] {...}

the compiler complains "Cannot convert ref string[][] to ref string[]" or "...ref string[,] to...".

I have no idea what I should use for that parameter.
Could someone please help?

Regards
Stephan