Porter generally prefers format strings to manual text concatenation, though he admits printf conversion tokens don't always stick in memory.

format-string.txt
myField.DataFormatString = "{0:#,##0." + new string('0', 2) + ";(#,##0." + new string('0', 2) + ")}";

Jasmine's co-worker wanted configurable decimal places. The solution joins two calls to `new string('0', 2)` in `myField.DataFormatString`. The result formats grouped numbers with two fractional digits and wraps negative values in parentheses. Porter accepts the intent but suggests extracting the repeated fragment to a `decimalPlaces` variable first.

While reviewing .NET documentation for custom numeric formats, Porter discovered the per-mille specifier requires the Unicode sign U+2030—awkward to type on most keyboards. A line like `string perMilleFmt = "#0.## " + '\u2030';` crosses into TRWTF territory.