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-GlobalFoundries 180um MCU 7 track standard cells libraries
+GlobalFoundries 180nm MCU 7 track standard cells libraries
 ==========================================================
 
 This repository contains the "7 track standard cells" implementation as part of
diff --git a/docs/symbols.rst b/docs/symbols.rst
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+=========================
+Reading Databook Symbols
+=========================
+
+========== ================================
+**Symbol** **Definition**
+0          Logic Low
+1          Logic High
+HL         High to Low Transition
+LH         Low to High Transition
+↑          Positive Clock Edge
+↓          Negative Clock edge
+Tin        Input Transition 30 to70 %
+Delay      50 to 50%
+Tout       Output Transition 30 to 70%
+?          Don't Care (Combinatorial Cells)
+X          Don't Care (Sequential Cells)
+default    No “when” condition for Input
+n/a        No Transition
+========== ================================