<para>

The external representation of an interval is formed using one or two

floatingpoint numbers joined by the range operator (<literal>..</literal>

floating-point numbers joined by the range operator (<literal>..</literal>

or <literal>...</literal>). Alternatively, it can be specified as a

center point plus or minus a deviation.

Optional certainty indicators (<literal>&lt;</literal>,

<literal>&gt;</literal>and <literal>~</literal>) can be stored as well.

<literal>&gt;</literal>or <literal>~</literal>) can be stored as well.

(Certainty indicators are ignored by all the built-in operators, however.)

<xref linkend="seg-repr-table"> giveson overviewover the allowed

<xref linkend="seg-repr-table"> givesan overviewof allowed

representations; <xref linkend="seg-input-examples"> shows some

examples.

</para>