Which of the following is correct when adding typecodes to existing typelists?

When adding typecodes to existing typelists, using the suffix "_Ext" is a best practice as it indicates that the new typecodes are extensions of existing typecodes. This serves a few important purposes:

1. Clarity: The suffix "_Ext" clearly identifies the new typecodes as extensions rather than foundational or default types. This helps maintain clarity when developers or users are interacting with the typelists and ensures that it is understood that these types were added after the original ones.

2. Avoiding Conflicts: By designating the typecodes as extensions, you reduce the likelihood of naming conflicts with any existing typecodes that may already be in use. This practice emphasizes that these are additional options rather than replacements or modifications of the original set.

3. Consistency: Following this naming convention promotes consistency across the codebase. If all extensions are marked with "_Ext", developers can quickly identify which code has been customized or added.

Using other suffixes like "_New," "_Type," or not adding anything special can be less informative and potentially lead to confusion. For example, "_New" may not convey that the items are meant to extend an existing list, while "_Type" could imply multiple concepts and is