4.1.2.1 Basic knowledge about the styles

There are nine image-names which define the control- and guide-symbols to draw the tree. Here is the list of the allowed image-names and the related corresponding ascii-symbols:

• - open (“[-]”): The control-symbol displayed for an opened tree-node which has several subnodes. Clicking onto this control closes the node.
• - close (“[+]”): The control-symbol displayed for a closed tree-node, i.e. an expandable node with subnodes but all subnodes are hidden. Clicking onto this control opened the node and displays its subnodes - if there are any. If it has no subnodes the empty-symbol will be displayed.
• - empty (“[x]”): The symbol displayed for an empty node. An empty node is a node which could have subnodes but has currently none.
• - leaf (“*”): The symbol displayed for a node which can not have any subnodes so it is a “leaf” in the tree.
• - guide (“ |”): The symbol used for drawing vertical “guide-lines” for opened nodes. See the example below.
• - no-guide (“ ”): Sometimes invisible guide-lines are needed to draw the tree.
• - end-guide (“ ‘”): The symbol used for the guide-line of the last subnode of an opened node.
• - handle (“-”): The symbol displayed before every subnode. Each handle is connected to a guide-line - either a normal guide or an end-guide.
• - no-handle (“ ”): An invisible handle.

A tree will be build-up with these elements like follows:

[-] node-with-subnodes      (open)
 |-[+] not-empty-subnode1   (guide+handle+close)
 |-[x] empty-subnode        (guide+handle+empty)
 `-[-] not-empty-subnode2   (end-guide+handle+open)
    |-* leaf-1              (no-guide+no-handle+guide+handle+leaf)
    `-* leaf-2              (no-guide+no-handle+end-guide+handle+leaf)