Index: trunk/archive/modules/include/phase2.h
===================================================================
--- trunk/archive/modules/include/phase2.h	(revision 757)
+++ trunk/archive/modules/include/phase2.h	(revision 906)
@@ -68,12 +68,21 @@
 			    );
 
+/** Overscan axis */
+typedef enum {
+    PS_OVERSCAN_NONE = 0,		///< No overscan subtraction
+    PS_OVERSCAN_ROWS = 1,		///< Subtract rows
+    PS_OVERSCAN_COLUMNS = 2, 		///< Subtract columns
+    PS_OVERSCAN_ROWS_FIT = -1,		///< Subtract a fit to rows
+    PS_OVERSCAN_COLUMNS_FIT = -2	///< Subtract a fit to columns
+} psOverscanAxis
+
 /** Subtracts an overscan and bias from the input image. */
 psReadout *phase2SubtractBias(psReadout *in, ///< Input image to be de-biased, and output
 			      const psImage *bias, ///< Bias (or dark) image to subtract
 			      const psImageRegionArray *regions, ///< Bias regions
-			      int overscanAxis, ///< 1 = subtract rows; 2 = subtract columns; -1 = fit rows;
+			      psOverscanAxis overscanAxis, ///< 1 = subtract rows; 2 = subtract columns; -1 = fit rows;
 					   ///< -2 = fit columns; 0 = no overscan
 			      const psStatsOptions *stat, ///< Statistic to use
-			      const psPolynomial1D *polySpec ///< Polynomial specification to use for fit
+			      psPolynomial1D *polySpec ///< Polynomial specification to use for fit
 			      );