Crosswalk Exercise

In this exercise you get some practice conducting a crosswalk. A crosswalk is carried out by comparing the definition of each entity and attribute in your database with entity and attribute definitions in the Cadastral Data Content Standard until you find the entity or attribute in the Standard which matches your database.

By working through this exercise, you will become familiar with the kind of crosswalk you will need to conduct when working on your own cadastral data. So, though this exercise uses for its example a small subset of BLM land and mineral records entities and attributes, think about your own data while you are doing this exercise. Don't worry if you do not completely understand everything about the BLM example used here.  The point is to get some practice doing a crosswalk.

Some Preliminary Information

This is an exercise in crosswalking entities and attributes between example BLM records and the Cadastral Data Content Standard.

Before actually going ahead with the crosswalk exercise, please take a few minutes to look at the information below.

The following are links essential to conducting the crosswalk in this exercise:

• a subset of the Cadastral Data Content Standard entity relationship diagram, specifically, five entities related to Agent.
• definitions for the attributes associated with the five Cadastral Agent entities.
• a subset of the Bureau of Land Management's a BLM entity relationship diagram, specifically seven entities related to Customer.
• definitions for the attributes associated with the seven BLM Customer entities.

1. First use the links shown above to look at the subsets of the entity relationship diagrams for the Standard and for the BLM data. For your convenience you may wish to print out each of these so you can look at them while doing the crosswalk.
2. Notice that the entities and attributes in each diagram have very different names, but that in general they apply to the same kind of information, that is, information about people owning rights to land, such as name, address, and so forth.
3. Next use the links above to look at the definitions of the entities and attributes. You may wish to print out these also, so you can refer to them conveniently while carrying out this exercise.
4. Once you are a little familiar with the entities, attributes and their definitions, proceed to the exercise below to conduct a crosswalk between the BLM records and the Cadastral Data Content Standard.

The Exercise - Crosswalking BLM Attributes to the Cadastral Data Content Standard

Listed below is a brief example of the kind of information which might be found in BLM's land records data. (Obviously, this is a fictitious example, made up for the purpose of this exercise.)

• John William Doe, Jr.
• previously known as Junior Doe, based on information received 5/14/94
• 57 Rural Highway D
• Smalltown, Wyoming
• doing business for profit as The Myland Company

Your job in this exercise is to identify the Cadastral Data Content Standard entity/attribute which matches the BLM entity/attribute you are given. You get to choose the Cadastral attribute from three possible answers provided.

To simulate a real crosswalk of attributes from BLM records to the Cadastral Standard, you will have to look up the definition of the BLM attributes, and then look up the definitions of the Cadastral attributes to find the Cadastral attribute that crosswalks to each BLM attribute. While it might be easier if we simply listed all the definitions below, or provided links directly to each definition, this would be a less accurate simulation of what it actually takes do a crosswalk, which often entails spreading out entity-relationship diagrams and lists of entities, attributes and definitions on a table or tacked to a wall and searching for the connections between two models.

A couple of rules and guidelines to bear in mind:

• some BLM attributes do not have a corresponding Cadastral attribute, so the answer may be "none".
• there may be instances when more than one BLM attribute crosswalks to the same Cadastral attribute.

"John" pertains to BLM entity/attribute customer_name/cust_idv_first_name. For this BLM attribute, the corresponding Cadastral Data Content Standard entity/attribute is (choose only one):

Links to the Course Sections and Modules: [Quick Reference] [Introduction] [Section 1: Purpose and Benefits of the Cadastral Data Content Standard] [Section 2: How the Standard Was Developed] [Section 3: Other Standards and Related Activities] [Section 4: Data Modeling Techniques, Rules and Diagram Conventions] [Section 5: Crosswalks, Translations, and Examples] [Section 6: Understanding Compliance with the Standard] [Section 7: Maintenance of the Standard] [Section 8: User and Technical Support] [County Recorder Module] [GIS Specialist Module] [Surveyor Module] [Glossary]