The syntax is as follows: <pt:standard.choose>
<pt:standard.when pt:test="stringToACLGroup('user=userid1,userid2,...;group=groupid1,groupid2,groupid3;').isMember($currentuser)">
    ... content ...
</pt:standard.when> 
<pt:standard.otherwise> 
    ... default content ...
</pt:standard.otherwise> 
</pt:standard.choose> 
The value for the pt:test attribute is case-sensitive. Multiple users or groups should be separated by commas, with semi-colons separating user values from group values. 
Example 1: 
<pt:standard.choose>
<pt:standard.when pt:test="isGuest($currentuser)">
    ... guest user content ...
</pt:standard.when> 
<pt:standard.otherwise> 
    ... logged in user content ...
</pt:standard.otherwise> 
</pt:standard.choose> 
The value for the pt:test attribute is case-sensitive. Since there can be multiple guest users in the portal, simply testing for user ID 2 (default guest user) does not work. 
Example 2: 
<pt:standard.choose> 
<pt:standard.when pt:test="stringToACLGroup('user=1;').isMember($currentuser)"> 
<title>welcome administrator</title></head> 
    ... secret administrator content ...
</pt:standard.when> 
<pt:standard.when pt:test="stringToACLGroup('user=200,201;group=200;').isMember($currentuser)"> 
<title>the 200 club</title></head> 
    ... content only group 200 or users 200 and 201 can see ...
</pt:standard.when> 
<pt:standard.otherwise> 
<title>everyone else    ... content any user can see ...
</pt:standard.otherwise> 
</pt:standard.choose>