Document timestamp design choice

1 files changed, 13 insertions, 0 deletions

diff --git a/README.org b/README.org
index 194c7f1..ffb460e 100644
--- a/README.org
+++ b/README.org
@@ -88,6 +88,19 @@ For easy version control
 Reviewing cards is done directly on their org source file
 (instead of storing pre-processed/generated cards in a separate folder
 or in a database).
+*** Timestamps Format
+The org-mode default timestamp format does not include timezone
+information and only hours and minutes of the time are stored.
+
+Because it includes the abbreviate name of the day (~%a~),
+timestamps can't be compared to each other using string comparison.
+
+They also include spaces which makes it hard to parse the timestamps
+in the review data table in awk..
+
+To avoid these issues, all timestamps added or used by org-fc are
+ISO8601 formatted (e.g. =2020-01-15T11:58:12=) using *UTC0* as the
+timezone.
 ** TODO Getting Started
 Before using this package, a few variables have to be set: