sep_get_key_name - get the key name associated with a key index
ierr= sep_get_key_name(tag_history,key_index,key_name)
tag of History File
Key Index of Header Key
Key Name of Header Key
-1= if fails for other reasons
0= if successful
+1= if tag_history is an Sep77 History File
+2= if tag_history is a Sep3d History File but no matching Key Index is in Header Format File
auxpar from the Header Format File for the parameter hdrkey"#" for a given key_index
sep3d