int getOffsetInFieldElement(int signatureIndex) {
			int offset = signatureIndex - functionSigIndex;
			if (offset >= 0 && offset <= length()) {
				return offset;
			}
			return -1;
		}
A field element of the function signature field. The individual elements that compose
a function signature should extend this class.
@param as the attributed string used to display this element.
@param row the row of the function signature where this field element starts.
@param column the column where this field element starts within the row.
@param functionSigIndex the function signature index
Ghidra/Features/Base/src/main/java/ghidra/app/util/viewer/field/FunctionSignatureFieldFactory.java