In addition to the types in Table 16-6, you can also define special bit flags that define extra processing information for each option. Combine these bit flags with the type values using a logical OR operation:

*The POPT_ARGFLAG_ONEDASH flag allows the longName to be used with one or two dashes, such as -upgrade or --upgrade.

*For bitmask options, the POPT_ARGFLAG_OR, POPT_ARGFLAG_NOR, POPT_ARGFLAG_AND, POPT_ARGFLAG_NAND, and POPT_ARGFLAG_XOR type flags tell the popt library to apply the given operation, OR, NOR, AND, NAND, or XOR, to the value if set. The POPT_ARGFLAG_NOT flag tells the popt library to negate the value first.

*You can also use the macros POPT_BIT_SET to set a bit and POPT_BIT_CLR to clear a bit.

*The POPT_ARGFLAG_OPTIONAL flag indicates that the argument value is optional.

*The POPT_ARGFLAG_DOC_HIDDEN flag tells popt to hide this option when displaying the help documentation. In other words, this is an internal option.

*The rarely used POPT_ARGFLAG_STRIP flag tells popt to consume an option and ignore it. This option is rarely used.

*The POPT_ARGFLAG_SHOW_DEFAULT flag tells popt to show the initial value of the argument for this option as a default when displaying a help message.