Preheat oven to 275 degrees F. Adjust oven rack to the lower third position. Add ham;,; covered, and bake according to instructions. About an hour and a half before ham is finished, begin glazing process. Turn oven up to 325 degrees.

Do one of Either:

• Mix together the pineapple tidbits, rum, brown sugar, soy sauce, and vinegar, and pour over ham. Baste at regular intervals,  about every 10 minutes.
• Add pineapple to a blender and break down into very small pieces. Add to small saucepan along with rum, brown sugar, soy sauce, and vinegar. Bring to a boil and watching closely to avoid a boilover, reduce by about 1/3. Pour half over ham and glaze with the remainder every 10 minutes.

With either method, slightly separate the top slices so the glaze has maximum surface area. Turn the pan in the oven if glaze is cooking unevenly. Add a bit of foil formed to an area if that area is in danger of burning before the rest of the glaze is nicely caramelized. Remove ham to rest for 20 to 30 minutes after it reaches 135 degrees F in the center of the ham nearing but not touching the bone.

Notes:

Most hams instruct to cook with the spiral side down. We prefer the ham cooked on its least attractive side and the cuts to the outside where they can get glazed and become a little chewy. Those pieces are prized in our family for their deep flavor.

If desired, the juices and glaze at the bottom of the pan can be defatted before serving and/or simmered to reduce, or just served as is.