Macro component contents are wrapped inside a span element. W3C validator reports and error like below

Line 13, Column 31: document type does not allow element "DIV" here; missing one of "APPLET", "OBJECT", "MAP", "IFRAME", "BUTTON" start-tag

<div id="mLxP1" class="z-div">

The mentioned element is not allowed to appear in the context in which you've placed it; the other mentioned elements are the only ones that are both allowed there and can contain the element mentioned. This might mean that you need a containing element, or possibly that you've forgotten to close a previous element.

One possible cause for this message is that you have attempted to put a block-level element (such as "<p>" or "<table>") inside an inline element (such as "<a>", "<span>", or "<font>").

Test case

1. Open simplemacro.zul in browser
2. Take html snapshot with chrome developer tools "Edit HTML" in elements tab
3. Go to http://validator.w3.org/ and swtich to "Validation by Direct Input"
4. Click Check

Expected: No error should be reported for macro component html elements (Note: Even though in this case a Div is a root element inside Macro component, there are other ZK component like Groupbox who have Div as root element and they will show similar error.

Actual: Above mentioned error is displayed for Macro component output