diff --git a/docs/source_docs/user_guide/inputs/output/plotfiles.rst b/docs/source_docs/user_guide/inputs/output/plotfiles.rst
index 18ddc4f946e146294165864c6a2a5f7a6c7fe0db..db4732bae80cd8227e992e3d5cc6d119061c1c5d 100644
--- a/docs/source_docs/user_guide/inputs/output/plotfiles.rst
+++ b/docs/source_docs/user_guide/inputs/output/plotfiles.rst
@@ -28,6 +28,9 @@ format (for debugging).
 | par_ascii_per_approx | Time period of the ascii particle output (approximate);               |    Real     | -1        |
 |                      | if -1 then particle ascii files will not be written at this frequency |             |           |
 +----------------------+-----------------------------------------------------------------------+-------------+-----------+
+| file_digits          | Number of digits to use in plotfile (plt[0-9]+) and checkpoint        |    Int      |  5        |
+|                      | (chk[0-9]+) filenames.                                                |             |           |
++----------------------+-----------------------------------------------------------------------+-------------+-----------+
 | ascent_int           | Frequency of ascent pipeline;                                         |    Int      | -1        |
 |                      | if -1 then ascent will not be called.                                 |             |           |
 +----------------------+-----------------------------------------------------------------------+-------------+-----------+