This manual page is not meant to be exhaustive. The complete documentation for this version of TEX can be found in the info file or manual Web2C: A TeX implementation.
The tftopl program translates a (program-oriented) font metric file to a (human-oriented) property list file. Thus, you can edit the contents of the TFM files, if the font designer has not done his or her job properly, or if you're encountering strange difficulties, or if you're just curious. It also serves as a TFM-file validating program, i.e., if no error messages are given, the input file is correct.
The pl_name is extended with .pl if it lacks a suffix. If pl_name is not given, standard output is used. Likewise, tfm_name is extended with .tfm if it lacks a suffix. Also, path searching is done for the .tfm file using the environment variable TEXFONTS. If that is not set, tftopl uses the system default.
The argument format to -charcode-format specifies how character codes are output in the PL file. By default, only letters and digits are output using the C integer code (i.e., in ASCII); the others are output in octal. (Unless the font's coding scheme starts with TeX math sy or TeX math ex, in which case all character codes are output in octal.) If format is ascii, all character codes that correspond to graphic characters, besides the left and right parentheses, are output in ASCII. Finally, if format is octal, all character codes are output in octal.