Stropping a knife is a finishing step. In principle, any blade may be polished by stropping. Stropping can also burnish (i.e. push metal around on) the blade. Stropping may bring a somewhat sharp blade to "like new" condition. ALGOL 68 implementations used ALGOL 60's approaches to stropping. This is called a "stropping regime". Another similar (and partially overlapping) syntactic trick is stropping. In source code programs, some stropping technique had to be used. In grebes, this is done more vigorously with an open bill and is termed "stropping". Stropping is not used in most modern languages. Stropping can also be used in the Nim programming language. Stropping is primarily associated with ALGOL and related languages in the 1960s. Stropping is a method to mark explicitly a letter sequence for a special purpose. While this is superficially similar to stropping, the semantics are different.