2.5.2.2 Function Names
The set of predefined functions for filter expressions is as follows:
AVERAGE ([ISO/IEC29500-1:2011] section 18.17.7.18)
COUNTA ([ISO/IEC29500-1:2011] section 18.17.7.53)
DATE ([ISO/IEC29500-1:2011] section 18.17.7.74)
FALSE ([ISO/IEC29500-1:2011] section 18.17.7.117)
LEN ([ISO/IEC29500-1:2011] section 18.17.7.193)
MID ([ISO/IEC29500-1:2011] section 18.17.7.210)
SUM ([ISO/IEC29500-1:2011] section 18.17.7.306)
TRUE ([ISO/IEC29500-1:2011] section 18.17.7.331)
UPPER ([ISO/IEC29500-1:2011] section 18.17.7.335)