snc/only_encrypted_gui is a SAP Parameter attribute which is used to control Enforce encrypted SAPGUI connections information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
If this parameter is set to "1", unencrypted SAP GUI connections are
rejected with an error message.
To encrypt SAP GUI connections, an SNC product with the QoP setting
"Encryption" is required. Selecting a lower QoP level (such as "
Integrity") is not sufficient to fulfill the required condition.
Unlike profile parameter
See SAP Parameter Documentation for full SAP documentation for this profile parameter.