Update a global temporary table in AMDP

Hi HANA experts,

I am writing a piece of code using AMDP. I have a few basic questions.  I'm wondering if you could help me.

1. Is local temporary table not supported in AMDP?
2. In order to avoid local temporary table, I created a global temporary table.  In which
   schema should I put this global temporary table?  “_SYS_BIC”?  Does the user by default
   have the authorization to create this table and insert/update/delete records in this
   table?
3. I wrote an UPDATE statement to update a record in this global temporary
   table.  The compiler immediately tell me that “SQLScript: feature not
   supported”.   What should I do? Delete the record and then re-insert it?

Thanks,

Xin