Wikipedia - Fibra di carbonio (it) carbon fibres type UHM

https://doi.org/10.1351/goldbook.C00837
Carbon fibres type UHM (ultra-high modulus) designates a class of @[email protected] having very high values of @[email protected] larger than $$600\ \text{GPa}$$ (i.e. greater than 55% of the theoretical $$C_{11}$$ value of @[email protected]).
Source:
PAC, 1995, 67, 473. (Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)) on page 482 [Terms] [Paper]