Modify / Delete: no

Create: yes.  

•Start new attribute with “CUS_” prefix

Example: CUS_MATERIALTYPE

Recommendation:  

Do not use reserved names. The reserved keywords depend on the RDBMS system used and should be looked up in the documentation of the respective RDBMS.

The following documents may also be helpful:  

oList of SQL reserved words - Wikipedia

oFAQs: What are the Reserved Words for Esri's File Geodatabase?

•Size constraints: see Section 5  

•DateTime fields: use UTC time (mandatory in Utility Networks version 6)

•Additional prefix can help to identify the purpose of the introduced attribute at any time:

oNET for network attributes (see Network Attributes section)

oSYM in relation to symbology

oCAL for attributes in relation to network calculation

oBI for attributes relevant to connecting to third-party systems (ERP, DMS...)

•Use *_ID for fields that serve as keys for communication with another system.  

It makes sense to manage the desired behavior on the network with the help of attribute rules.