# Reply To: Trig symbol R

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The image you shared is of a letter R in the “double struck” or “blackboard bold” print typeface. This is commonly used for letters that refer to sets of numbers (e.g. ℝ for real numbers, ℤ for integers, ℕ for natural numbers).

11.6 of the UEB Guidelines for Technical Material says, "Embellished capital letters are often used to name common sets such as the universal set E, the set of real numbers R or integers I. These vary in print from book to book but can be **represented in braille by the script typeform indicators.**"

You are correct that we should use the script typeform for your example, and the appropriate transcription is ⠈⠆⠰⠠⠗ ("script symbol indicator grade 1 symbol indicator capital R")

Thank you for asking!

–Kyle