By default the maximum no. of windows which one can open in SAP for that system is 6. So, in essence a user can open 6 sessions in 4.7x.
Like, one set this values in rdisp/max_alt_modes parameter then he can change this parameter using RZ10 in instance profile and use extended maintenance for changing this.
Most of the companies prohibits these no. of sessions but not increase it since they can result unecessary load..
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