I did not find the answer on documentation for this question.
As we know, div.container gives
<div class="container">
However, what abbreviation shall be used for
<div class="row placeholders">
Anyone knows? Thanks.
From the Emmet Cheat Sheet:
p.class1.class2.class3 <p class="class1 class2 class3"></p>
So, div.row.placeholders
will give you:
<div class="row placeholders"></div>