CSS what's the difference in syntax?

[CSSquestion]

Hi all... I was wondering if any of you CSS pros could tell me the difference between these.

a.class
a.class:link
.class a:link

Also I've had issues with link classes when grouping them together with others

For example all the classes below would work properly except the link class:
.class p, .class .Normal, .class a:link{
font-family: Tahoma;
font-size: 10px;
font-style: normal;
line-height: 10px;
font-weight: normal;
color: #8E8B7A;
}

If I separate the link by itself it will work...but why?
below worked.

.class p, .class .Normal{
font-family: Tahoma;
font-size: 10px;
font-style: normal;
line-height: 10px;
font-weight: normal;
color: #8E8B7A;
}
.class a:link{
font-family: Tahoma;
font-size: 10px;
font-style: normal;
line-height: 10px;
font-weight: normal;
color: #8E8B7A;
}

Thanks.

[rbjarnason]

Hi
this it the difference in the syntax.
a.class refers to all the anchor tags with the class of 'class ' applied
a.class:link same as the above but you are now attaching style to the pseudo :link the w3c has the actual definitions of the pseudo's
.class a:link you are now referencing any anchor that is a child element of a tag with the class of 'class' applied to it. eg <li class='class'><a>you are referencing me</a></li>