A defined component tag (for example {selectComponent}) takes 0 or more parameters:

Additional parameters represent unsually HTML tag parameters and depend on the component we use.

A component making use from the datasource parameter can read the data for example from an external array instead of using {listItem} tags.

{selectComponent name="interests" datasource="$listItems"}
  {param name="selected" value="$selected"/}

  {onMessage message="msg" position="up"}
    <p>Error: {@msg}</p>
  {/onMessage}
{/selectComponent}

An undefined component tag takes at least one parameter:

Additional parameters represent unsually HTML tag parameters and depend on the component we use.

The tag allows to set additional parameters for the component.

For example, selectComponent uses it to get to know, which list element is selected.

If the component operates on lists, you may define static list items using this tag.

Sometimes you use the same event in many different places. You may write it only once and store it in the compiler memory under a specified ID using bindEvent instruction. This tag allows to load such shared events into the component.

{bindEvent id="messageEv" name="onMessage" message="msg" position="down"}
<p>Error: {@msg}</p>
{/bindEvent}
...
{selectComponent name="interests"}
   {load event="messageEv"/}
{/selectComponent}
...
{inputComponent name="age"}
   {load event="messageEv"/}
{/inputComponent}

This code could be also written as:

{selectComponent name="interests"}
   {onMessage message="msg" position="down"}
    <p>Error: {@msg}</p>
   {/onMessage}
{/selectComponent}
...
{inputComponent name="age"}
   {onMessage message="msg" position="down"}
    <p>Error: {@msg}</p>
   {/onMessage}
{/inputComponent}

However, as you see, it is less clear and harder to modify (especially if there is a large number of components and we want to make the events display above, not under the component). Note that you may put the shared events in the master template.

All other tags defined inside the component are called event tags. An event is a piece of HTML that may be shown around the component, if some event occured (for example, the data are invalid). They are mostly used to display error messages, when the specified form data do not match to the patterns.