HTML code <%%> <% =%> <%:%> What is the meaning of each were used to achieve what??

<% Here write programming language such as C # daemon%>, <% = herein may take the background non-proprietary variable value%>

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Can be written between <%> server-side code, such as
<%
for (var I = 0; I <10; I ++) {
// perform loop body
}
%>
Again
<%
for (var I = 0; I < 10; I ++) {
%>
// iteration of the loop (in this case the loop of html language )
<%}
%>;

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<% =%> Variable acquired background values, such as a background session [ "ab"] = "ab"; front <% = session [ "ab"]%> can be taken to a value;

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<%:%>同<%=%>