Jobs are a confusing part of the NetSuite system. Here’s some notes and resources to help make handling jobs easier:

• Jobs are named Projects in the GUI
• There are two versions of jobs: “standard” and “Advanced Jobs”. They both use the same core job record but change how the data is structured on the customer.
• Jobs have a kcustomer attribute that is not accessible via SuiteTalk which represents the customer that the job is associated with. This field is accessible via SuiteScript. You could most likely expose this field by creating a formula field on the job record with {kcustomer} as the formula.
• There is no customer field on the job schema
• However, there is a customer field on the job search columns. You can use an advanced search to return the customer associated with a job.
• If “Project Management” is enabled (aka ADVANCEDJOBS) the entity reference on the customer is a customer during the edit view, but will switch to be a job reference when the record is saved.
• When ADVANCEDJOBS is disabled the job reference could be either a customer or a job and the job field is not displayed.
• The parent field on a job can reference a customer. I believe you can have an heirarchy of jobs so it can be possible for the parent to be a job reference. Since the kcustomer field is not exposed via SuiteTalk the only way to determine the correct customer reference is to walk up the hierarchy.

References:

• Determine the customer associated with a job via SuiteTalk
• SuiteScript to extract a valid customer reference from an entity ID
• Determining if an entity ID is a customer or a project