Why APPLPTMP should point to shared filesystem in an RAC environment?

Hello all,According to doc "Using Oracle 11g Release 2 Real Application Clusters with Oracle E-Business Suite Release 12 [ID 823587.1]", in section 3.9.2 item 9, APPLPTMP should be pointing to a directory on a shared file system.

I'd like to know the reason for this requirement and what would be the impact if the directory pointed by APPLPTMP is not a shared file system.

Is there a situation where one concurrent program executes in one db session and other db session related to that concurrent program needs to read/write same temp file(s) generated by the first session?

Thanks

Luís Morimoto