If the parameter "sortable=yes" is specified, the template generates invisible text that will cause the column to sort correctly in sortable tables. However, it is at the cost of having that invisible text read out audibly by many screen readers. "Col 1" without the template does not sort correctly. "Col 2" with the template and sortable=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}} |
| 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}} |