# open_hours v1.0.1 - Table of Contents > Time calculations using business hours ## Modules - [OpenHours](OpenHours.md): Documentation for OpenHours. - [OpenHours.Common](OpenHours.Common.md) - [OpenHours.Duration](OpenHours.Duration.md): This module contains functions to calculate business time duration. - [OpenHours.Interval](OpenHours.Interval.md): This module contains functions for working with intervals of time. - [OpenHours.Offset](OpenHours.Offset.md): This module provides business time arithmetic operations. - [OpenHours.Schedule](OpenHours.Schedule.md): This module contains functions to work with schedules. - [OpenHours.TimeSlot](OpenHours.TimeSlot.md): This module contains all functions to work with time slots.