Css block nomeclature

The videos are helpful but in the Apple design model ther are times when a new block is labeled:

.product element

.product .element

.product .element .element

Is BSS inferring the nesting from where the cursor is when New is clicked?

Therefor you must create a top-level block before any elements are added and all the rest are inherit this name and BSS infers the nesting for the new block name. Correct?