Matched context for essential and extra

The page lists matched contexts for essential and extra.

Share - essential	Share - extra	Phrase
6.30%	4.54%	{essential or extra} [importance] component
14.79%	1.85%	{essential or extra} [importance] part
0.38%	2.67%	{essential or extra} [importance] valve
0.31%	2.25%	{essential or extra} [importance] step