Several predefined variables are available in the Source script field.

VariableTypeDescription
source GlideRecord The record from the source table that is currently being processed.
target GlideRecord The record from the target table that is currently being processed.
answer String The field value to set in the target record.
map GlideTransformMap Read-only information about the current transform map record.
log Function The log object for the current import run. Use this object to log messages such as log.info("<Message>") or log.warn("<Message>"). This object logs to the import log for standard import sets, or other log locations as required, such as for web service imports.
action String Contains either the value insert or update, depending on whether the current target row will be created or updated.
Note: The action variable is available only when the Coalesce field is false.