Application Component

I am building a new application on a new system. The expression type CRM Web Request was not visible among the available expression types. A search of the web failed to uncover a reason.

A colleague instructed me to set the value of Application Component on my application to "CRM". I did this and the CRM Web Request expression appeared.

I then did a second search of the web looking for why this should work. I still failed to find anything telling me I should have used this value. There is no drop down list of values for the field.

The help on https://help.sap.com/saphelp_crm700_ehp03/helpdata/en/40/ecd7d31a4f4636b0c337f0426213dc/content.htm?frameset=/en/ec/d04d2cc6334587b529b144c97f5a61/frameset.htm

says to leave the field blank.

Can someone point me to where is the help this value is described?

Thanks

Cliff