A call to oft2-marker has the following syntax:
Usage: otf2-marker [OPTION] [ARGUMENTS]... ANCHORFILE
Read or edit a marker file.

Options:
                      Print all markers sorted by group.
      --def <GROUP> [<CATEGORY>]
                      Print all marker definitions of group <GROUP> or of
                      category <CATEGORY> from group <GROUP>.
      --defs-only     Print only marker definitions.
      --add-def <GROUP> <CATEGORY> <SEVERITY>
                      Add a new marker definition.
      --add <GROUP> <CATEGORY> <TIME> <SCOPE> <TEXT>
                      Add a marker to an existing definition.
      --remove-def <GROUP> [<CATEGORY>]
                      Remove all marker classes of group <GROUP> or only the
                      category <CATEGORY> of group <GROUP>; and all according
                      markers.
      --clear-def <GROUP> [<CATEGORY>]
                      Remove all markers of group <GROUP> or only of category
                      <CATEGORY> of group <GROUP>.
      --reset         Reset all marker.
  -V, --version       Print version information.
  -h, --help          Print this help information.

Argument descriptions:
  <GROUP>, <CATEGORY>, <TEXT>
                      Arbitrary strings.
  <SEVERITY>          One of:
                       * NONE
                       * LOW
                       * MEDIUM
                       * HIGH
  <TIME>              One of the following formats:
                       * <TIMESTAMP>
                         A valid timestamp inside the trace range
                         'global offset' and 'global offset' + 'trace
                         length'.
                       * <TIMESTAMP>+<DURATION>
                         <TIMESTAMP> and <TIMESTAMP> + <DURATION> must be valid
                         timestamps inside the trace range 'global
                         offset' and 'global offset' + 'trace length'.
                       * <TIMESTAMP-START>-<TIMESTAMP-END>
                         Two valid timestamps inside the trace range 'global
                         offset' and 'global offset' + 'trace length', with
                         <TIMESTAMP-START> <= <TIMESTAMP-END>.
                      See the CLOCK_PROPERTIES definition with the help
                      of the 'otf2-print -G' tool.
  <SCOPE>[:<SCOPE-REF>]
                       The <SCOPE> must be one of:
                       * GLOBAL
                       * LOCATION:<LOCATION-REF>
                       * LOCATION_GROUP:<LOCATION-GROUP-REF>
                       * SYSTEM_TREE_NODE:<SYSTEM-TREE-NODE-REF>
                       * GROUP:<GROUP-REF>
                       * COMM:<COMMUNICATOR-REF>
                      <SCOPE-REF> must be a valid definition reference of
                      the specified scope. Use 'otf2-print -G' for a list of
                      defined references.
                      There is no <SCOPE-REF> for <SCOPE> 'GLOBAL'.
                      For a scope 'GROUP' the type of the referenced
                      group must be 'OTF2_GROUP_TYPE_LOCATIONS' or
                      'OTF2_GROUP_TYPE_COMM_LOCATIONS'.