property |NSURL| : a reference to current application’s |NSURL|
property NSOrderedSet : a reference to current application’s NSOrderedSet
property NSURLTagNamesKey : a reference to current application’s NSURLTagNamesKey

set anAlias to (choose file)
clearTagsForPath(anAlias) of me –delete tags
set aRes to getTagsForPath(anAlias) of me –check

— clear all tags
on clearTagsForPath(anAlias)
　　set aURL to |NSURL|’s fileURLWithPath:(POSIX path of anAlias)
　　aURL’s setResourceValue:{} forKey:(NSURLTagNamesKey) |error|:(missing value)
end clearTagsForPath

— get the tags
on getTagsForPath(anAlias)
　　set aURL to |NSURL|’s fileURLWithPath:(POSIX path of anAlias)
　　set {theResult, theTags} to aURL’s getResourceValue:(reference) forKey:(NSURLTagNamesKey) |error|:(missing value)
　　if theTags = missing value then return {} — because when there are none, it returns missing value
　　return theTags as list
end getTagsForPath

— set the tags, replacing any existing
on setTagsForPath(tagList, anAlias)
　　set aURL to |NSURL|’s fileURLWithPath:(POSIX path of anAlias)
　　aURL’s setResourceValue:tagList forKey:(NSURLTagNamesKey) |error|:(missing value)
end setTagsForPath

— add to existing tags
on addTagsForPath(tagList, anAlias)
　　set aURL to |NSURL|’s fileURLWithPath:(POSIX path of anAlias)
　　— get existing tags
　　set {theResult, theTags} to aURL’s getResourceValue:(reference) forKey:(NSURLTagNamesKey) |error|:(missing value)
　　if theTags ≠ missing value then — add new tags
　　　　set tagList to (theTags as list) & tagList
　　　　set tagList to (NSOrderedSet’s orderedSetWithArray:tagList)’s allObjects() — delete any duplicates
　　end if
　　aURL’s setResourceValue:tagList forKey:(NSURLTagNamesKey) |error|:(missing value)
end addTagsForPath