There are quite a few definitions in the RID which end ก็ว่า, though this isn't a structure I can find in any of my grammar reference books. Can anyone please explain what precisely it means and when it's appropriate to use it? Thanks.

A few example definitions using this structure:

กรมกรอม ก. ระทมใจจนเหี่ยวแห้ง, ตรมตรอม ก็ว่า.
กระโงก (กลอน) น. นกยูง, กุโงก ก็ว่า. (เทียบ ข. โกฺงก).
กระจุ๋มกระจิ๋ม ว. เล็ก ๆ น้อย ๆ น่าเอ็นดู, จุ๋มจิ๋ม ก็ว่า.

I am guessing it means "is also said" or "is also used" because it appears after variant forms.

Basically seconded. I suppose one could go for the literal "is also uttered", as it is also used after mere spelling variants in one dictionary I use.

I'm not sure that works with a definition such as:

อัตนัย ว. ที่เปิดโอกาสให้แสดงความรู้หรือความคิดเห็นส่วนตัวได้,
เรียกการสอบแบบที่ให้ผู้ตอบบรรยายแสดงความรู้หรือแสดงความ
คิดเห็นของตนเองว่า การสอบแบบอัตนัย, คู่กับ ปรนัย, จิตวิสัย ก็ว่า.
(อ. subjective).

It works, it says that การสอบอัตนัย and การสอบปรนัย are a pair, (big comma there) จิตวิสัย is another way of saying อัตนัย

If you look up จิตวิสัย then it should mean similar, they are both about an individual's ability or imagination.

Edit: I have just noticed: subjective exam and objective exam, if that means anything to you.

จิตวิสัย is a synonym of อัตวิสัย, an antonym of ปรวิสัย

It means "subjective," as apposed to "objective."

In another thread, "The Beauty of The Thai Language - A True Story," a poster found the Thai language to be simplistic and crude.

This is an example of a subjective view.

It is a view based on the person viewing, his taste, prejudice, etc., and valid as such.

The opposite is the objective view ปรวิสัย, which is based on the merits of the object being viewed, it must then be examined via factual evidence.

Another word pair you should look into is อัตลักษณ์ vs. เอกลักษณ์

As for the ก็ว่า, it's literally "also said."

ปรนัย and อัตนัย are the words designated by the RI to translate objective and subjective when they appear.

I don't see it working from Thai to English.

สอบอัตนัย examining subjectivity Subjective exam. Someone more recently in the school system may be able to guess what this is. From the Thai it seems to be more like an interview.

เอกลักษณ์ อัตลักษณ์ are good words.

เอกลักษณ์ is in the dictionary as identity, but I think it means one characteristic shared by a group by which they can be identified.

อัตลักษณ์ isn't in the dictionary so is it a person's characteristics which would identify them?

[สอบอัตนัย examining subjectivity Subjective exam. Someone more recently in the school system may be able to guess what this is. From the Thai it seems to be more like an interview. ]

สอบอัตนัย a test requiring an essay.

Sorry I noticed that I shortened it from การสอบแบบอัตนัย .

I wonder if สอบอัตนัย makes sense, can you give any examples of อัตนัย being used?

[Sorry I noticed that I shortened it from การสอบแบบอัตนัย .]

You don't have to spell it out.

[I wonder if สอบอัตนัย makes sense, can you give any examples of อัตนัย being used? ]

Yes, and in keeping with this line, ข้อสอบอัตนัย.