Can one combine audit conditions in unified audit policy

Hi,

I wonder if one can combine an audit condition when creating a audit policy.

I need to audit proxy users connects except those with a specific os_username.

The documentation of "create audit policy" describes that one can use

Numeric functions: BITAND, CEIL, FLOOR, POWER

Character functions returning character values: CONCAT, LOWER, UPPER

Character functions returning number values: INSTR, LENGTH

Environment and identifier functions: SYS_CONTEXT, UID

Comparison conditions: =, !=, <>, <, >, <=, >=

Logical conditions: AND, OR

Null conditions: IS [NOT] NULL

[NOT] BETWEEN condition

[NOT] IN condition

my policy looks like:

create audit policy mp_proxy_pol_2

actions all

when 'SYS_CONTEXT(''USERENV'', ''PROXY_USER'') IS NOT NULL