R devel - Feb 2020 - PDF generation issue from manual page

Hi R gurus

Got an issue risen by CRAN about using unknown characters from Latex.

Here is the error message







*Check: PDF version of manual, Result: WARNING   LaTeX errors when creating
PDF version.   This typically indicates Rd problems.   LaTeX errors found:
  ! Undefined control sequence.   <recently read> \blacktriangleright *




*   l.237 STRATUM $\blacktriangleright
$ LAYER\_3   ! Undefined control sequence.   <recently read>
\blacktriangleright *




*   l.239 PHASING $\blacktriangleright
$ RUN   ! Undefined control sequence.   <recently read>
\blacktriangleright
*

*   l.241 INTENT  $\blacktriangleright
$ FEEDBACK*

I understand that the \blacktriangleright is an unknown control sequence
from latex ... and that sounds strange to me, as I uses it often in
vignettes without any issue so far.

In the incriminated manual page, the code generating this sequence is the
following
*\ifelse{latex}{\out{$\blacktriangleright$}}{\ifelse{html}{\out{&#x25B6;}}{\u25b6}}*

I am wondering what is wrong and how to circumvent such issue.
Yours ideas and hints welcome

Best.
Neonira

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