If the parameter "sortable=yes" is specified, the template generates invisible text that will cause the column to sort correctly insortabletables. However, it is at the cost of having that invisible text read out audibly by manyscreen readers. "Col 1" without the template does not sort correctly. "Col 2" with the template andsortable=yes sorts correctly.

{|class="sortable wikitable"style=text-align:right;|-! Title!!Col 1!!Col 2|-|style=text-align:left;| Foo|| 1066|| 1066|-|style=text-align:left;| Bar|| c. 1510||{{circa|1510|sortable=yes}}|-|style=text-align:left;| Baz|| 1956|| 1956|-|style=text-align:left;| Jaz|| c. 410||{{circa|410|sortable=yes}}|}