For example, if you had a batch file called stuff.bat and you typed stuff a b c d at the command prompt, the letters a, b, c, and d would be assigned to the variables %1, %2, %3, and %4, respectively.
Fiberglass shingles generally have a longer life expectancy than do asphalt shingles. Properly installed tiled roofs have a normal useful life of 20-30 years or longer, but individual pieces can become cracked or broken or the nails rust out.
Typically you can expect 10 years of hassel-free life out of average shingles. Depending on the factors above, you can expect to do minor repairs/patching in the 10-15 year range. After 15 years or so, you should probably start budgeting for new shingles.