xuantong bowl

[mark123]

Was this bowl made during the reign of the Xuantong emperor?

[peterp]

It has a Xianfeng reign mark. However,  with the worm back foot rim it would have to be imperial, but imperial marks would more likely have used zhuanti characters than these. Then, the ? character does not show a certain trait that many marks of the period would exhibit.
Are there any clear age or usage signs?