This is an interesting use case for GREP styles. While it would be great to have a zero-width pseudo font or similar solution, another option could be to create a custom character style that changes the color to match the background, effectively hiding the text. For the underlining feature, using a character style to visually replace symbols with underlines is indeed common in language textbooks. It would be great if more software incorporated these kinds of flexible text manipulation tools for specialized formatting needs. You can explore more related ideas at textinvisible.com.
Anam
This is an interesting use case for GREP styles. While it would be great to have a zero-width pseudo font or similar solution, another option could be to create a custom character style that changes the color to match the background, effectively hiding the text. For the underlining feature, using a character style to visually replace symbols with underlines is indeed common in language textbooks. It would be great if more software incorporated these kinds of flexible text manipulation tools for specialized formatting needs. You can explore more related ideas at textinvisible.com.