[Boost-users] How to parse_config_file with blank key value?

Summary: Is it possible for the program_options parse-config-file capability to support a config file that has a "blank" keyword value as per this config file example: ---- cut here ---- username= password= ---- cut here ---- This file would be parsed as if there's no value set for these keys/parameters/settings. More background: I manage a development group that uses Boost, and our developers aren't sure how to do this, and I'm posting on their behalf. The answer is not obvious to me at: http://boost.org/doc/html/parse_config_file.html Are there other, pertinent docs? We want to do this to assist the users of our software to know which values *can* be set...without setting them in a default config file. -Matt