Changes in doc/lgf.dox [162:33247f6fff16:201:9757e3d9bfeb] in lemon-1.2

File:

• doc/lgf.dox (modified) (3 diffs)

doc/lgf.dox

@@ -47 +47 @@
 
 The \c \@nodes section describes a set of nodes and associated
-maps. The first is a header line, it columns are the names of the
+maps. The first is a header line, its columns are the names of the
 maps appearing in the following lines.
 One of the maps must be called \c
@@ -65 +65 @@
 
 The \c \@arcs section is very similar to the \c \@nodes section,
-it again starts with a header line describing the names of the arc,
+it again starts with a header line describing the names of the maps,
 but the \c "label" map is not obligatory here. The following lines
 describe the arcs. The first two tokens of each line are
@@ -79 +79 @@
 \endcode
 
-The \c \@edges is just a synonym of \c \@arcs.
+The \c \@edges is just a synonym of \c \@arcs. The @arcs section can
+also store the edge set of an undirected graph. In such case there is
+a conventional method for store arc maps in the file, if two columns
+has the same caption with \c '+' and \c '-' prefix, then these columns
+can be regarded as the values of an arc map.
 
 The \c \@attributes section contains key-value pairs, each line
-consists of two tokens, an attribute name, and then an attribute value.
+consists of two tokens, an attribute name, and then an attribute
+value. The value of the attribute could be also a label value of a
+node or an edge, or even an edge label prefixed with \c '+' or \c '-',
+which regards to the forward or backward directed arc of the
+corresponding edge.
 
 \code