[...]
       compopt [-o option] [-DEI] [+o option] [name]
              Modify completion options for each name according to the options, or for  the  cur-
              rently-executing  completion  if  no  names are supplied.  If no options are given,
              display the completion options for each name or the current completion.  The possi-
              ble values of option are those valid for the complete builtin described above.  The
              -D option indicates that other supplied options should  apply  to  the  ``default''
              command completion; that is, completion attempted on a command for which no comple-
              tion has previously been defined.  The -E option indicates that other supplied  op-
              tions  should  apply to ``empty'' command completion; that is, completion attempted
              on a blank line.  The -I option indicates that other supplied options should  apply
              to completion on the inital non-assignment word on the line, or after a command de-
              limiter such as ; or |, which is usually command name completion.

              The return value is true unless an invalid option is supplied, an attempt  is  made
              to  modify  the options for a name for which no completion specification exists, or
              an output error occurs.
[...]

compopt: compopt [-o|+o option] [-DEI] [name ...]
    Modify or display completion options.
    
    Modify the completion options for each NAME, or, if no NAMEs are supplied,
    the completion currently being executed.  If no OPTIONs are given, print
    the completion options for each NAME or the current completion specification.
    
    Options:
        -o option       Set completion option OPTION for each NAME
        -D              Change options for the "default" command completion
        -E              Change options for the "empty" command completion
        -I              Change options for completion on the initial word
    
    Using `+o' instead of `-o' turns off the specified option.
    
    Arguments:
    
    Each NAME refers to a command for which a completion specification must
    have previously been defined using the `complete' builtin.  If no NAMEs
    are supplied, compopt must be called by a function currently generating
    completions, and the options for that currently-executing completion
    generator are modified.
    
    Exit Status:
    Returns success unless an invalid option is supplied or NAME does not
    have a completion specification defined.