PER_EXT_PAY_EMPLOYEES_V2_UE Entity Where clause

Hi We are using PER_EXT_PAY_EMPLOYEES_UE in one of our extracts.

the Entity query has below where clause.

AND ppa.payroll_relationship_id = pprd.payroll_relationship_id

AND paaf.work_terms_assignment_id = ppa.hr_term_id

AND trunc(&b1) BETWEEN papf.effective_start_date AND papf.effective_end_date

AND trunc(&b1) BETWEEN paaf.effective_start_date AND paaf.effective_end_date

AND trunc(&b1) BETWEEN pprd.start_date AND pprd.end_date

AND trunc(&b1) BETWEEN ppa.start_date AND ppa.end_date

AND trunc(&b1) BETWEEN papd.start_date (+) AND papd.end_date (+)

From where does the bind parameter value(&b1) is picked up?