Schedules

A schedule controls the dates and times available for the performance of a service and/or the use of a resource. One schedule applies to one service or resource, since each service or resource can be reserved independently of the others. (If two or more services, people, locations, or things cannot be reserved independently of one another, they are considered to be one activity or resource.) A schedule consists of slots of time during which the controlled service or resource is potentially available for performance or use. Slots are categorized as open, booked, or blocked. An open slot on a schedule indicates that the service or resource is available for performance or use during that period of time. A booked slot indicates that the service or resource is not available during the time period, because an appointment has been scheduled. A blocked slot indicates that a service or resource is unavailable for reasons other than a scheduled appointment.

The real-world, non-automated analog of the schedule described above is a standard appointment book. These books are generally organized with rows of time slots, during which a service or resource is available. The following figure illustrates an excerpt from such an appointment book.

Each cell in the figure above represents a slot on a schedule. Different shading patterns represent booked and blocked slots. Information identifying the appointments scheduled in booked slots is written in the appointment book. Similarly, explanations are written into the book when resources are blocked. Those cells with no shading and comments represent open slots.

As in the figure above, appointment books commonly contain more than one column. This format allows the scheduling of more than one resource or activity within the same book. This chapter defines a schedule as an entity controlling the availability of only one resource or service for a given period of time. Given that definition, each column in the above excerpt from the appointment book represents a separate schedule for a separate resource.

Services and Resources

Services and resources are the "what" in any communication of scheduling transactions, that is, they are things—either tangible or intangible—that the transaction is attempting to affect or describe. The services and resources that are controlled by schedules are typically in high demand. In any case, their use or performance is managed through the process of reserving blocks of time.

Services are typically activities that occur in a certain location, where specific people and equipment exist to carry out the activity. The activity must be scheduled prior to its occurrence. The schedule that controls the activity may not be the same schedule that controls the location, people, and equipment. For example, patient visits to a clinic are typically controlled through scheduling. Patients receive an appointment at the clinic, and at the appointed time are seen by a member of the clinic staff. From the point of view of the person or application requesting the appointment for the patient, the "thing" being scheduled is a service (e.g., a doctor's consult, an X-ray, etc.). The assignment of an exam room and (in this example) a physician, nurse practitioner, or other staff member is incidental to the actual appointment.

Resources are tangible things that must be reserved prior to their use. Examples might include MRI equipment, portable X-ray machines, or rooms. People are also tangible resources that are often scheduled. Typically these people controlled by schedules have special roles, perform special activities, and are in high demand.

The following are the primary attributes that describe a resource:

• A unique identification code
  
  The unique identification code for a service or resource describes a specific instance of that service or resource. For tangible resources, this may be a serial number, a location, an employee number, or another unique designation. For services, the identification of a slot on the schedule is usually sufficient for unique identification.

• A code describing the type of class of service or resource
  
  This code describes a type or class of service, or resource groups like services or resources together. For services, this is typically a universal service ID similar to the field used in the OBR segment defined in the Order Entry chapter (Chapter 4). This Universal Service ID uniquely identifies clinical services performed in a healthcare provider organization.
  
  For tangible resources, this code may be a model number, a staff classification (such as physician, nurse, physical therapist, etc.), or a kind of room. This kind of information can be used to request a resource from a pool, where a specific instance of the resource scheduled is unknown and unimportant (as long as it is of the specified type or class).

• A name or text description of the resource
  
  The name or text description of the resource provides a human-readable identification of the service or resource.

• When a resource is associated with an appointment, or is requested for an appointment, the following attributes describe the relationship (or requested relationship):

• The start date and time the service or resource is required for the appointment.
  
  The start date and time the service or resource is required for the appointment describes the point at which the service or resource should be made available to the activity. In this specification, this is represented as a positive or negative time offset from the start date and time of the appointment.

• The duration for which the service or resource is needed for the appointment.
  
  The duration for which the service or resource is required for the appointment describes how long the service or resource is needed to complete the appointment. By adding the duration to the start date and time, the end date and time can be calculated for the required resource or service within the activity.

• Other attributes further describe services and resources. These attributes are communicated, as necessary, in transactions between applications.

Appointments

Appointments are instances of the performance of a service or the use of a resource. They describe the "why," the "who" and the "when" in any communication of scheduling transactions. These appointments occupy one or more slots on a service or resource schedule, causing those slots to become unavailable or "booked." Appointments can describe scheduled activities related to patients in a healthcare setting, or they can describe scheduled activities wholly unrelated to patients.

In its simplest form, an appointment consists of one service or resource reserved for a period of time, for a specific reason. More complex activities involve multiple services or resources, or parent-child relationships to other appointments.

The primary attributes for the appointment which describes a scheduled activity include the following:

• A unique placer appointment identification code
  
  The placer appointment identification code uniquely describes an instance of an appointment. It is used in communications between placer and filler applications to identify a particular appointment (or a request for an appointment booking) on the placer application. Except in special circumstances, the code is assigned by the placer application upon making an initial scheduling request. This concept is similar in practice to the placer order number found in Chapter 4, Order Entry.

• A unique filler appointment identification code
  
  The filler appointment identification code uniquely describes an instance of an appointment. It is the filler application's counter-part to the placer appointment identification code. It is used in communications between placer and filler applications to identify a particular appointment (or request for an appointment booking) on the filler application. Except under special circumstances, it is assigned by the filler application when an appointment (or a request for an appointment booking) is created by the filler application. This concept is similar in practice to the filler order number found in Chapter 4, Order Entry.

• An appointment start date and time
  
  The appointment start date and time describe the beginning of the appointment. In request transactions, the appointment start date and time are expressed as a preference or list of preferences. The filler application uses this expression of preference to book the appointment. Once an appointment has been booked, the start date and time are expressed in the actual scheduled start date and time.

• An appointment duration
  
  The appointment duration describes how long the appointment will last, and consequently, the end date and time of the appointment.

Supporting information about service and resource activities includes the following:

• Reason codes to describe the reason that the service is occurring or the resource is being used;

• Patient information to describe for whom the appointment is taking place, whether the appointment or scheduled activity is for, or related to, a patient;

• Requestor information to describe the person responsible for initiating and executing the appointment;

• Location information to describe where the appointment is scheduled to occur.

Other attributes further describe appointments. These attributes are communicated as necessary in transactions between applications.

Parent and Child Appointments

Parent appointments are those appointments that embody one or more child appointments. For example, a request for a repeating appointment results in a logical parent (the original scheduled appointment request), and one or more children (each individual occurrence of the appointment). This specification provides no information about how individual applications store or handle parent and child appointments, but it does provide a mechanism for identifying individual occurrences (children) within transactions.

Either the placing application or the filling application can specify child appointments—and in one of two ways. If each individual child appointment is assigned a separate and unique Placer Appointment ID and/or Filler Appointment ID, then that unique identifier may be used in transactions to specify an individual child. If, however, neither the placer nor filler application assigns a unique identifier separately, an occurrence number can be used. Both the ARQ and SCH segments allow for an occurrence number, which is a unique serial number assigned to each child within a parent appointment.

The Filler Application Role

The filler application role in the scheduling model is very similar to the filler application concept presented in Chapter 4, Order Entry. A filler application, in the scheduling model, is one that "owns" one or more schedules for one or more services or resources. In other words, a filler application exerts control over a certain set of services or resources and the schedules that define the availability of those services or resources. Because of this control, no other application has the ability to reserve, or to otherwise modify, the schedules controlled by a particular filler application.

Other applications can, on the other hand, make requests to modify the schedules owned by the filler application. The filler application either fulfills or denies requests to book slots, or to otherwise modify the schedules for the services and resources over which it exerts control.

Finally, the filler application also provides information about scheduled activities to other applications. The reasons that an application may be interested in receiving such information are varied. An application may have previously requested bookings or modifications on the schedule, or may simply be interested in the information for its own reporting or statistical purposes. There are two methods whereby filler applications disseminate this information: by issuing unsolicited information messages, or by responding to queries.

The analog of a filler application in a non-automated environment might be an appointment book and the person in charge of maintaining that book. The appointment book describes when the resources are available and when they are booked. This appointment book is the only official record of this information, and controls the availability of the resources to any user. The person in charge of this appointment book takes requests to book the resources, and decides whether to accept or reject the requests based on the information recorded in the appointment book. Anyone needing information from the appointment book either consults the book directly, or contacts the person in charge of the book.

The Placer Application Role

The placer application role in the scheduling model is also very similar to its counterpart in the Order Entry chapter. A placer application requests the booking, modification, cancellation, etc., of a scheduled activity for a service or resource. Because it cannot exert any control over the schedule for that resource, it must send its requests to modify the schedule to the filler application. In requesting that these appointments be booked or modified in some way, the placer application is asking the filler application to exert its control over the schedule on the placer application's behalf.

The analog of a placer application in a non-automated environment might be any person needing a particular resource or appointment for a service. A person needing to book an appointment would contact the person in charge of the appointment book for that resource or service, and request a reservation. Often, there is negotiation between the person requesting the reservation or appointment and the person who maintains the appointment book. The requesting person will indicate requirements and preferences, and the person controlling the appointment book will indicate whether the request can be fulfilled as specified.

The Querying Application Role

A querying application neither exerts control over, nor requests changes to a schedule. Rather than accepting unsolicited information about schedules, as does an auxiliary application, the querying application actively solicits this information using a query mechanism. It will, in general, be driven by a person wanting information about schedules, and may be part of an application filling the placer application role as defined in this chapter. The information that the querying application receives is valid only at the exact time that the query results are generated by the filler application. Changes made to the schedule after the query results have been returned are not communicated to the querying application until it issues another query transaction.

The analog of a querying application in a non-automated environment might be any person needing information about a specific portion of a schedule. For example, a facilities manager may need to know whether a specific room has been scheduled during a specific period of time. This person might ask the person controlling the appointment book about the specific room and period of time in question.

Often, a placer application will also act as a querying application. The ability to send queries and receive lists of open slots is built in to some implementations of placer applications. These placer applications use this information to select open slots for subsequent booking requests. The current specification does not imply that placer applications should or should not also be able to fulfill the role of a querying application. Instead, the model defines these roles separately. Applications that support this functionality may take advantage of this application role in the model. Applications that do not support the querying application role are not limited in their support of the placer application role.

The Auxiliary Application Role

Like querying applications, an auxiliary application neither exerts control over, nor requests changes to a schedule. It, too, is only concerned with gathering information about a particular schedule. It is considered an "interested third-party," in that it is interested in any changes to a particular schedule, but has no interest in changing it or controlling it in any way. An auxiliary application passively collects information by receiving unsolicited updates from a filler application.

The analog of an auxiliary application in a non-automated environment might be any person receiving reports containing schedule information. For example, a facilities manager may need to know what rooms are booked for activity during specific periods of time. This person might ask the person controlling the appointment book for a periodic listing of activity, which may be something as simple as copies of pages from the appointment book.

Often, a placer application will also act as an auxiliary application. A placer application may have the capacity to store information about the scheduled activity that it requested. In such cases, the placer application is also an "interested" application in that it wishes to receive any messages describing changes to the content or status of the scheduled activity it initiated.

Application Roles in a Messaging Environment

In a messaging environment, these four application roles communicate using specific types of messages and trigger events. The following figure illustrates the relationships between these application roles in a messaging environment:

The relationship between placer and filler applications revolves around request messages and response messages to those requests. Placer applications trigger request messages to filler applications, which respond to those requests with request response messages.

The relationship between querying and filler applications focuses on query messages and responses. Querying applications trigger query messages to filler applications, which respond with query response messages.

The relationship between auxiliary and filler applications centers on unsolicited informational messages. Filler applications trigger unsolicited informational messages to auxiliary applications whenever changes in the schedule occur. Auxiliary applications do not respond with any messages other than general acknowledgments. Filler applications triggering unsolicited informational messages do not expect further information from auxiliary applications.

Trigger Events

The trigger events for this chapter are defined in Section 10.3, "PLACER APPLICATION REQUESTS AND TRIGGER EVENTS,” 10.4, "FILLER APPLICATION MESSAGES AND TRIGGER EVENTS UNSOLICITED," and 10.5, "QUERY TRANSACTIONS AND TRIGGER EVENTS." Traditionally, trigger events define the transition of some entity from one state to another.¹ Typical trigger events may be listed as follows: new, cancel, modify, discontinue, reschedule, and delete.

[1]     HL7 trigger events are not strictly limited to this definition; however, most trigger events do define state transitions.

Status

The status of a scheduled activity describes where that activity is in its life cycle. A status differs from a trigger event in an important way: a status describes the current condition of an entity, whereas a trigger event is generated to "move" the entity from one state to another. All status fields in this chapter are defined with respect to the application acting in the role of a filler, unless otherwise (and specifically) indicated. Therefore, a status in a scheduling interface transaction is only truly meaningful if the transaction was generated by the application assigning or maintaining that status.

Typical statuses for a schedule transaction might include the following: pending, wait-listed, confirmed, canceled, discontinued, deleted, started, completed, overbooked (booked for a resource along with another conflicting appointment), blocked, etc.

Reasons

This chapter defines two kinds of reasons used with transactions. The first is an appointment reason that indicates why the appointment is being booked – and ultimately why the activity is going to occur. The second is an event reason that describes why a particular trigger event has been generated. Reasons tend to be static, whereas statuses tend to change. In contrast, trigger events describe an action to be performed.

Appointment reasons tend to be relatively static for the life of the scheduled activity. Typical examples of appointment reasons include the following: routine, walk-in, check-up, follow-up, emergency, etc.

Event reasons are static as well, but only for the life of a particular trigger event. Typical examples of event reasons include the following: no-show (e.g., when an appointment is canceled), at patient request, at caregiver request, etc.

Types

Rather than describing why an appointment has been scheduled – as the appointment reason does – the appointment type describes the kind of appointment recorded in the schedule. This information tends to be administrative in nature. Typical appointment types might include: normal, tentative (or "penciled in"), STAT, etc.

Appointment

An appointment represents a booked slot or group of slots on a schedule, relating to one or more services or resources. Two examples might include a patient visit scheduled at a clinic, and a reservation for a piece of equipment.

Auxiliary Application

An auxiliary application neither exerts control over, nor requests changes to a schedule. It is only concerned with gathering information about a particular schedule. It can be considered an "interested third-party," in that it is interested in any changes to a particular schedule, but has no interest in changing it or controlling it in any way. It may gather information passively or actively. An auxiliary application passively collects information by receiving unsolicited updates from a filler application.

Block

An indication that a slot or a set of slots is unavailable for reasons other than booking an appointment.

Book

The act of reserving a slot or set of slots on a schedule for a service or resource.

Child Appointment

A child appointment is an appointment subordinate to another appointment (called a parent appointment). For example, a single instance of an appointment in a group of recurring appointments is a child to the group. Child appointments can themselves be parent appointments. For example, if a battery of appointments is scheduled, then the atomic units of the battery are children to the battery request. If the battery is scheduled as a repeating appointment, then each instance of the battery of appointments (parent to each of the atomic units) is a child to the original repeating request.

Filler Application

The filler application role in the scheduling model is very similar to the filler application concept presented in Chapter 4, Order Entry. A filler application, in the scheduling model, is one that "owns" one or more schedules for one or more services or resources. It fulfills requests to book slots for the services or resources over which it exerts control. It also notifies other applications of activity related to appointments, such as new bookings, modifications, cancellations, etc.

Parent Appointment

A parent appointment is an appointment that consists of one or more subordinate appointments (called child appointments). A parent appointment is used to relate or group multiple appointments together in various ways. Examples of kinds of parent-scheduled activities include, but are not limited to, the following.

• Recurring (repeating) appointments. For example, a physical therapy appointment may be scheduled every Tuesday at 4:00 PM for three months.

• Batteries of appointments. For example, an activity consisting of an appointment with Radiology, an appointment with a specialist, and an appointment with a primary care physician might be scheduled.

• Complex appointments. For example, recurring batteries of appointments, or batteries of battery appointments.

Parent appointments can themselves be children to other appointments.

Placer Application

The role of the placer application in the scheduling model is also very similar to its counterpart in the Order Entry chapter. A placer application must request the booking, modification, cancellation, etc., of an appointment for a service or resource because it cannot exert any control over that service or resource on the schedule. In requesting that these appointments be booked or modified in some way, the placer application is asking the filler application to exert its control over the schedule on the placer application's behalf.

Querying Application

A querying application neither exerts control over nor requests changes to a schedule. Rather than accepting unsolicited information about schedules, as does an auxiliary application, the querying application actively solicits this information using a query mechanism. It will be driven by a person wanting information about schedules, and may be part of an application filling the placer application role as defined in this chapter. The information that the querying application receives is valid only at the exact time that the query results are generated by the filler application. Changes made to the schedule after the query results have been returned are not communicated to the querying application until it issues another query transaction.

Resource

A resource is any person, place or thing that must be reserved prior to its use.

Schedule

A schedule is the sum of all of the slots related to a service or resource.

Service

A service is any activity that must be scheduled prior to its performance.

Slot

A slot is one unit on a schedule. A slot represents the smallest unit of time or quantity that a service or resource may be booked. Depending on the nature of the service or resource, there may be more than one defined slot at a given instant of time. For example, if a service is an open group therapy session with twelve available seats, then there are twelve slots for the given block of time.

Update mode

This chapter uses the "Action code/unique identifier" mode for updating via repeating segments. For more information on updating via repeating segments, please see section 2.10.4, "Protocol for interpreting repeating segments or segment groups in an update Message," in Chapter 2. The definition of the "Action code/unique identifier" update mode can be found in Chapter 2, Section 2.10.4.2, "Action code/unique identifier mode update definition."