When using the xhtml1-transitional.dtd doctype, collecting a credit card number with the following HTML

<input type="text" id="cardNumber" name="cardNumber" autocomplete='off'/>

will flag a warning on the W3C validator:

there is no attribute "autocomplete".

Is there a standards-compliant way to disable browser auto-complete on sensitive fields in a form?

html forms w3c-validation
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