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# Question marks handling

Possible continuations are treated special way in therion in both centerline and map files. You may associate text description, explored length (behind this continuation) or any other atribute to it (like Code if you have your own coding standard for continuations).

## Question marks in centerline

In the centerline object, you may add a special flags to the station, where continuation is possible. Just use following syntax

    station 5 "pit" continuation attr Code V explored 20m

When you export map and use

    symbol-show point flag:continuation

in your layout, station with continuation flag specified is marked by question mark (continuation symbol is shown above the station).

You may redefine continuation symbol to show also continuation description (stored in `_text` attribute) using following layout code

    code metapost
      def p_continuation(expr pos,theta,sc,al) =

        % draw default continuation symbol
        p_continuation_UIS(pos,theta,sc,al);

        % if text attribute is set
        if known(ATTR__text) and picture(ATTR__text):

          % set labeling color to light orange
          push_label_fill_color(1.0, 0.9, 0.8);

          % draw filled label with text next to ?
          p_label.urt(ATTR__text,(.5u,-.25u) transformed T,0.0,8);

          % restore original labeling color
          pop_label_fill_color;

        fi;
      enddef;
    endcode

Then also continuation description is displayed in the map.

## Question marks in maps

In the scrap (.th2 file), you can use `-text`, `-code` and `-explored` options to continuation symbol.

    point 796.0 676.0 continuation -attr Code A -explored 50m \
        -text "water too cold to continue survey"

In the map, also the question marks only are displayed by default.

When you redefine continuation symbol as mentioned above, you can show also continuation codes and descriptions.

## Exporting question mark lists

You may also export a list of all continuations from your project project using

    export continuation-list -o questions.html

File questions.html then contains following list:

Comment | Explored | Survey | Station | Code
--- | --- | --- | --- | ---
water too cold to continue survey | 50.0 | Sample cave | 7 | A
strong wind from breakdown |  | Sample cave | 3 | B
pit | 20.0 | Sample cave | 5 | V

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