Sorcha, I don't see any ampersand codes in your HTML but your 300 and 400 are showing on my IE browser but not on Netscape.

I don't know what the range is but computers typically blocks of bytes (8 bits) a single byte gives 2^8 = 256 (0 to 255) values, 2 bytes would be 2^16 = 65536.

Looking at the 2 browsers, I would guess that the range is 0-255. One method computers use in handling out of range numbers is to "wrap round", e.g. On a single byte, 256 would yeild 0, 257 yeilds 1, etc. Maybe IE does that and Netscape treats it as an error.

Jon