serious problem

[rockbergema]

this

[Oleg]

explore properties of this .mesh object - you could see it's dimensions (bounding size) and vertices/polygons count in properties too. This would give you a hint on how big this object and whether it has any geometry or not (may be it's a single tiny triangle and the whole .ydr file for head is just to store a good skeleton there).

In case you are dealing with a modded content, the .ydr file for the head could contain anything from "nothing" to entire ped/player model.

[rockbergema]

Now

[Oleg]

well, ZModeler will not load this model. The model has an evidence of locking and ZModeler can't load such a model. The locking was removed by some means to let ZModeler "try to load it", but the model is still corrupt inside (intended locking scenario), so ZModeler does not load it.

The author of this model decided to prevent his/her models from being edited, so the model was released locked. I don't know who or when removed locking info from a file, it doesn't really matter - ZModeler will still reject to load such a file.

Also, it is possible the model was made with OpenIV open formats with "Locking" option enabled. ZModeler can not see this locking info on a file, but still can't load such a locked model.

[rockbergema]

Okay oleg, thanks for the information