1.Standard Internal Tables: These tables have a linear index
and can be accessed using the index or the key. The response
time is in linear relationship with number of table entries.
These tables are useful when user wants to address
individual table entries using the index.
2.Sorted Internal Tables: These tables also have an index
and the key. But, the response time is in logarithmic
relationship with number of table entries, since it uses
binary search algorithm instead of linear search. These
tables are useful when user wants the table to be sorted
while additional entries have to be added. 
3.Hashed Internal Tables: These tables have no index, but
have the key. The response time is constant irrespective of
number of table entries, since it uses a Hash algorithm.
These tables are useful when user wants to access the
entries with key only. 

INTERNAL TABLE TYPES, ATTRIBUTES IN VER. 4.X
============================================

	         A N Y    T  A  B  L  E
	         |            |
	    INDEXED          NON INDEXED
	    TABLES           TABLES - HASHED TABLES
	    |    |
	STANDARD  SORTED
	 TABLES   TABLE

	SY-TABIX  SY-TABIX     SY-TABIX INOPERTIVE (NO 
INDEXED 
  OPERATIONS)

	L SEARCH  B SEARCH     HASHED ALGO FOR SEARCH

	B SEARCH
	IF SORTED
	& SPECFIED

	ACCESS TIME DEPENDS    ACCESS TIME INDEPENDENT OF 
ENTRIES
	ON NO OF ENTRIES

	S,D KEY   D KEY        DEFINED KEY

	N UNIQUE  N UNIQUE     UNIQUE KEY
	          UNIQUE

	RESORT    NO RESORT    RESORT