USFM 3.0

[DavidHaslam]

Need to add the new markers defined in USFM 3.0 which is currently at rc1 stage.

See http://ubsicap.github.io/usfm/about/releasenotes.html#about-release-3-0

[DavidHaslam]

ParaTExt 8.1 will use USFM 3.0.

[DavidHaslam]

My syntax highlighter does not yet include the nested syntax for character styles.

e.g. \+xt ...\+xt*