Limitation on tag lenght

[Milind Joshi]

Is there any limitation on the length of the tag in digiKam? I am using 
IPTC tags which are compatible with other programs like darktable, Gimp, 
IrfanView etc. One of the reasons I am not using the xmp tags is that 
IrfanView does not display the xmp information. I have noticed that some 
of the tags are truncated when they are written to tif files, hence 
would like to know the limit.

Also, does this limit apply to individual tags or to a tag and its sub tags?