[Proj] UTM Zone projection parameters to pass to pj_transform()

[Jacques, David - Fort Worth, TX]

Dear list...

I am using proj4.4.9 and libgeotiff to read multiple geotiff headers in
order to
 reproject the bounding box from UTM to geographic for an inventory
tracking map.
 However my sample output points from the pj_transform() function are
not correct.

 Below are the input & output coordinate systems, each with their
corresponding line in the epsg file.

  //<26915> +proj=utm +zone=15 +ellps=GRS80 +datum=NAD83 +units=m
+no_defs  <>
  static char *utm15n_parms[] =
{"proj=utm","zone=15","ellps=GRS80","datum=NAD83","units=m","no_defs"};

  //<4326> +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs  <>
  static char *ddwgs84_parms[] =
{"proj=longlat","ellps=WGS84","datum=WGS84","no_defs"};


What other parameters are needed for the UTM coordinate system ?  
Its supposed to be UTM Zone 15N NAD83 GRS80


Regards


David