1. Revised the definition of nano calcium carbonate.

2. Modified the composition indicators of nano calcium carbonate.

3. Modified the specific surface area index, added restrictive instructions for surface treatment compared to surface area testing, and clarified the static capacity BET method.

4. Deleted the content related to TEM observation of the morphology of nano calcium carbonate particles.

5. The grain size (XRD method) indicator and measurement method have been removed.

6. The aggregation index indicator and measurement method have been removed.

7. The method for measuring oil absorption value has been removed.

8. Deleted the method for determining insoluble substances in hydrochloric acid.

9. Appendices A, B, C, and D have been deleted.

10. Added the whiteness index of nano calcium carbonate.

11. Added moisture index and measurement method for nano calcium carbonate (Appendix).