A magnetic tape (1) characterized by having a backcoating layer (5) which comprises a binder and fine particles having been dispersed in the binder and being capable of irreversibly changing in color on oxidation reaction, and has a sufficient number of microvoids of sufficient size to supply sufficient oxygen to cause the oxidation reaction.
This application is a continuation and claims the benefit of priority under 35 USC 120 of U.S. application Ser. No. 10/341,739, filed Jan. 14, 2003, now abandoned, U.S. application Ser. No. 10/170,830, filed Jun. 13, 2002, now abandoned, and U.S. application Ser. No. 09/530,005, filed Jul. 21, 2000, now abandoned. In addition, this application claims the benefit of priority under 35 U.S.C. 119 of: 371 PCT/JP98/04767, filed Oct. 21, 1998, which claims the benefit of Japanese Application Number 9-289885, filed Oct. 22, 1997.
