SPECTRE_RF_POSTLAYOUT_EAP Environment Variable

In the "Getting The Most Out Of Spectre APS" application note, slide 11 recommends

"For RF analyses – If Spectre 17.1 ISR11 or newer, use HPA and setthe environment variable SPECTRE_RF_POSTLAYOUT_EAP to 1 – For older versions of Spectre, use Legacy-RF RCR"

I have confirmed that I am using Spectre 17.1 ISR11 (specifically that release); should I be able to query this environment variable from the CIW with getShellEnvVar("SPECTRE_RF_POSTLAYOUT_EAP")?

Also, is setShellEnvVar("SPECTRE_RF_POSTLAYOUT_EAP=1") in the CIW the correct way to set this?

Lastly, what does this environment variable do and is it a recommendation or required to use the new +postlayout with SpectreRF?