gt = selects greater than  보다큰 :  if gt IE 6 ->  현재버전 > 6
lt = selects less than 보다 작은 :  if lt IE 6 ->  현재버전 < 6
gte = selects greater than or equal to 같거나 큰  :  if gte IE 6 ->  현재버전 >= 6
lte = selects less than or equal to 같거나 작은  :  if lte IE 6 ->  현재버전 <= 6

To select exclusivly for any  non IE  - use " IE  & !IE " for a downlevel-revealed within a downlevel-hidden CC
<!--[if IE]><![if !IE]><![endif]-->  html  <!--[if IE]><![endif]><![endif]-->

To select for  IE 5.01 only  - use " IE 5.0 " or "lte IE 5.0" or "!gt IE 5.0" or "lt IE 5.5000" or "!gte IE 5.5000"
<!--[if IE 5.0]>  html  <![endif]-->

To select for  IE 5.5 or 6 or 7.0  - use " !IE 5.0 " or "!lte IE 5.0" or "gt IE 5.0" or "!lt IE 5.5000" or "gte IE 5.5000" (all less specific)
<!--[if !IE 5.0]>  html  <![endif]-->

To select for  IE 5.5 only  - use " IE 5.5000 "
<!--[if IE 5.5000]>  html  <![endif]-->

To select for  IE 5.01 or 6 or 7.0  - use " !IE 5.5000 " (less specific)
<!--[if !IE 5.5000]>  html  <![endif]-->

To select for  IE 6 only  - use " IE 6 "
<!--[if IE 6]>  html  <![endif]-->

To select for  IE 5.01 or 5.5 or 7.0  - use " !IE 6 " (less specific)
<!--[if !IE 6]>  html  <![endif]-->

To select for  IE 7.0 only  - use " IE 7.0 "; or less specific "!lte IE 6" or "gt IE 6" or "!lt IE 7.0" or "gte IE 7.0" or "!lt IE 7" or "IE 7" or "gte IE 7"
<!--[if IE 7.0]>  html  <![endif]-->

To select for  IE 5.01 or 5.5 or 6  - use " lte IE 6 " or "!gt IE 6" or "lt IE 7.0" or "!gte IE 7.0" or "lt IE 7" or "!gte IE 7"; or less specific "!IE 7.0" or "!IE 7"
<!--[if lte IE 6]>  html  <![endif]-->

To select for  IE 5.01 or 5.5  - use " IE 5 " or "lte IE 5" or "!gt IE 5" or "lte IE 5.5000" or "!gt IE 5.5000" or "lt IE 6" or "!gte IE 6"
<!--[if IE 5]>  html  <![endif]-->

To select for  IE 6 or 7.0  - use " !IE 5 " or "!lte IE 5" or "gt IE 5" or "!lte IE 5.5000" or "gt IE 5.5000" or "!lt IE 6" or "gte IE 6" (all less specific)
<!--[if !IE 5]>  html  <![endif]-->

To select for  IE 5.01 or 6  - use " lte IE 6  & !IE 5.5000 " or, more general, any of 3 pairs ({"lt IE 7", "!IE 7", "lte IE 6"},{"!IE 5.5000"}) for a downlevel-revealed within a downlevel-hidden CC
<!--[if lte IE 6]><![if !IE 5.5000]>  html  <![endif]><![endif]-->

To select for  IE 5.01 or 7.0  - use " !IE 6  & !IE 5.5000 " (less specific) for a downlevel-revealed within a downlevel-hidden CC
<!--[if !IE 6]><![if !IE 5.5000]>  html  <![endif]><![endif]-->

To select for  IE 5.5 or 6  - use " lte IE 6  & gte IE 5.5000 " or, more general, any of 9 pairs ({"lt IE 7", "!IE 7", "lte IE 6"},{"gt IE 5.0", "!IE 5.0", "gte IE 5.5000"}) for a downlevel-revealed within a downlevel-hidden CC
<!--[if lte IE 6]><![if gte IE 5.5000]>  html  <![endif]><![endif]-->

To select for  IE 5.5 or 7.0  - use " !IE 6  & gt IE 5.0 " or, more general, any of 3 less specific pairs ({"!IE 6"},{"gt IE 5.0", "!IE 5.0", "gte IE 5.5000"}) for a downlevel-revealed within a downlevel-hidden CC
<!--[if !IE 6]><![if gt IE 5.0]>  html  <![endif]><![endif]-->

To select for  IE 5.01 or 5.5 or 6 or 7.0  - use " lte IE 7.0 "; or less specific "gte IE 5" or "gte IE 5.0" or "lte IE 7" or "IE"; it seems not feasible to use any negations for this selection.
<!--[if lte IE 7.0]>  html  <![endif]-->