[OSM-newbies] Is there any tag for say "seeing in"?

[Xan]

Hi,

Is there any tag for say "I saw this thing in this date"? I think it's 
useful for knowing when things are change. I explain: we have tag data 
for tagging the date of construction or date when the things are finished.

But suppose we have a park. One user tags all of its parts (in 
2010-09-24). It's perfect and there is no missing thing. One month 
after, in this park, the Administration adds a playground. Another user 
adds this playground (in 2010-11-24). Could these users see 
"I-see-in=2010-09-24" and "I-see-in=2010-11-24"?

This is different from a user tagging this park uncompletely in 
2010-09-24 and another user completes the tag in 2010-09-25. Because the 
"version" of the park in this case is the same.

So, "I-see-in" could provide information about if the things change or 
there are new elements.

Regards,
Xan.