Description of the problem

Based on the documentation at https://docs.generic-mapping-tools.org/dev/plot.html#s it should be possible to rotate the symbols of a decorated line by appending +aangle:

+aangle
Force symbols at a fixed angle, +an for line-normal, or +ap for line-parallel [Default].

However, so far this does not work for me. For quoted lines, it works to rotate the label by appending +aangle.
Related PyGMT comment GenericMappingTools/pygmt#2564 (comment).

Full script that generated the error

Input data: test_data_deco_line.txt

gmt plot test_data_deco_line.txt -R0/10/-1/1 -JX10c/3c -B -S~d2c:+ss1c+a20 -W1p,black -png deco_lines_rot_gmt

Full error message

No error message occurs.

Actual outcome

Expected outcome

The squares along the line should be rotated by 20 degrees (counter-clockwise from the horizontal); similar to quoted lines:

gmt plot  test_data_deco_line.txt  -R0/10/-1/1 -JX10c/3c -B -Sqd1c:+ltext+a20 -W1p,black -png quot_lines_rot_gmt

System information

• Operating system: Windows-10-10.0.19045-SP0
• GMT version (gmt --version): 6.4.0 as well as 6.5.0_95c3431_2023.06.26