login/accept_sso2_ticket is a SAP Parameter attribute which is used to control Accept SSO tickets for this (component) system 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 .
You can use Single Sign-On (SSO) tickets to allow SSO between SAP
systems, and even beyond to non-SAP systems. An SSO ticket can be a
logon ticket or an assertion ticket. The logon ticket is transferred as
a cookie with the name MYSAPSSO2. The assertion ticket is transferred as
an HTTP header variable with the name MYSAPSSO2. Note that this requires
additional configuration steps for the issuing and accepting systems.
SSO component systems should permit logon by SSO ticket
(login/accept_sso2_ticket = 1).
If only the procedure (X.509 client certificates) is used for Single
Sign-On, or if you do not want to use Single Sign-On for this system,
you can deactivate logon by SSO ticket (login/accept_sso2_ticket = 0).
See SAP Parameter Documentation for full SAP documentation for this profile parameter.