An example of a cool filter is ImageMagick but it was not written with the NCBI toolkit. Here's how one uses ImageMagick - a program called convert takes a number of arguments. It figures out the first file as the input and writes out the second file as the output. Here's the asntool command to convert a Biostruc from binary to ascii. BUT it is usually missing the Biostruc data.
Filters are programs that are often command-line oriented.
For systems like Macintoshes or for people frightened by command-lines, one must provide a visual interface. In the NCBI toolkit, there is a standardized scheme for reading in program arguments which automatically provides a command-line and a visual interface depending on the platform and the compile options chosen. Here's the arguments used for a program that only needs a single file. Next 15 Jan 1998. C.W.V. Hogue .