Browse Implementation
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1. OPC XML-DA is very flexible in defining requirements for server paths and
   items design. As unique item indentifier is used conncotenated ItemName
   and ItemPath values. There are both of them can be constructed from any
   printable Unicode characters.
   For browsing pruposes uses some tree structure (not depended at all on
   this ItemPath) any opc item can be "directory", "item" or both of them.
   
   For implementation diecided to use most common unix directory structure (
   including soft links). Only exclusion: any "item" may be as well "directory"
   and vice versa. By design this should be used to provide additional 
   information about HDR items (like data description).
   
	Such combined item can be freeily destroyed from creator plugin. In
	case it still needed as "directory" only "item" part will be really
	destroyed. Directory will be destroyed automatically later when it
	will go out of neccesarity.
   
   Still it isn't very difficult to reimplement this in other way. Most
   method depended code is in: 
	opctree.c
	opcitem.c
	opcserver.c/RegisterItem()


2. Because of "Browse" is long procedure and can be done in several client 
   requests it's unclear when apply filters. Information can be changed
   during interval between client requests. Following approach now is 
   used:
	Apply all filters on first request. On effective requests of items
	only presistance will be checked. All information about item 
	properties will be requested only on client's effective request.
    another approach would be:
	To get on first request only list of items. But all filters also apply
	on effective request.
    It's hard to say wich way is correct. Second one will give a bit more 
    contemporary information, still first one more traditional and requires
    less computational power. 
    
    Still because of modular organization it's only several lines of code to 
    change between this implementations. Most method depended code is in:
	opcitem.c/opcItemBrowse
	opcserver.c/???