I took some time, sometime ago, to standardize the way I integrate my PHP and X/HTML in my files. I did it passively, and over time.
Integrating PHP and X/HTML together generally occurs when working within views of an MVC codebase/project.
I believe it's a pretty important note to make, as it can make your code exceptionally more readable, and thus maintainable. This is especailly true for new-comers to your codebase and style. Here is some sample code from a codebase, and I'll follow that up with how I would reformat it using my standard.
<?php if (($obj && $obj->property) || $other): ?> <div id="user"> <?php if ($obj->sub && $obj->num === 4): ?> <p class="paragraph<?php if ($true) echo ' margin-fix'; ?>">Sample Copy <strong><?php echo h($obj->title); ?></strong></p> <?php endif; ?> <?php if ($obj->yellow): ?> <div class="class-name"> <div class="float-left"> <?php echo linkTo(Helper::stringHelper($obj->colour, 'Yay! The colour is: ' . h($obj->colour)), formatColour($obj->colour), array('class' => 'img-wrapper')); ?> </div> <div class="left school-detail"> <p class="pre-note">Featured in</p> <p><strong><?php echo linkTo('The School of ' . h($school->name), schoolUrl($school)); ?></strong></p> </div> </div> <?php endif; ?> </div> <?php endif; ?>