X_OPERAND_TYPE is a fixed lexicon with the following values:

Saved
Value
Displayed ValueNameDescription
$C $CUser Variable
$F $FProcessing Frequency
$G $GGlobal Variable
$L $LList
$P $PParameter
$S $SSystem Constant
$V $VSystem Variable
A AAlphanumeric
AC ACAction Code
B BBoolean
CE CEElement to Calendar Date
CF CFCustom FunctionThe list of Custom Functions as defined in X_UC_FUNCTIONS.See that page as well as CREATE A USERCALC CUSTOM FUNCTION
CH CHCharacterThis is for special characters like ENTER, SPACE and TAB – which cannot be entered using the A (Alphanumeric) operand type
CL CLCalendar
D DDate
DB DBDatabase Field
DV DVDatabase Value
EC ECCurrent Element Value
EF EFFiscal to Date Element Value
EM EMMonth to Date Element Value
EP EPPeriod to Date Element Value
EQ EQQuarter to Date Element Value
ET ETTransaction to Date Element Value
EY EYYear to Date Element Value
FT FTPension Factor
N NNumber
NV NVNew Value
OV OVOld Value
PC PCPay Component - Current (N)These three will expect a user to provide a pay component code value to get the value for the current pay, fiscal month to date, calendar month to date (same idea as PY)
PF PFPay Component - Fiscal to DateThese three will expect a user to provide a pay component code value to get the value for the current pay, fiscal month to date, calendar month to date (same idea as PY)
PM PMPay Component - Month to DateThese three will expect a user to provide a pay component code value to get the value for the current pay, fiscal month to date, calendar month to date (same idea as PY)
PN PNPension ComponentThis refers to the Pension Components used in the Retirement Module
PP PPPay Component - Period to DateThese two will expect a user to provide a pay component code value to get the value for the pay period to date and the calendar quarter to date (same idea as PY)
PQ PQPay Component - Quarter to DateThese two will expect a user to provide a pay component code value to get the value for the pay period to date and the calendar quarter to date (same idea as PY)
PT PTTransactions To Date PC Value
PY PYYear-to-date PC Value
RT RTRecipient Type
S SStatistical Component Value
SN SNSundry Life to Date
UC UCUser Calc Calculation
UF UFUser Calc Function/Qualifier
V VLocal Variable
WB WBWage Basis