add optical and DSP PM min/max spec

doc/platform_api/CMIS_and_C-CMIS_support_for_ZR.md

@@ -1050,6 +1050,29 @@ def get_TX_configured_power(port):
 ```
 
 #### 3.2 Get VDM related information
+
+The table below specifies the threshold for important optics and DSP performance metrics:
+
+
+|PM| Min| Max|
+|--|--|--|
+|PreFEC BER|0| 1.25E-2|
+|PostFEC BER| |0|
+|Tx Power (dBm)| | | 
+|Rx Power (dBm)| | | 
+|OSNR (dB/0.1nm)|26| |
+|SNR (dB)|13.6| |
+|CD (ps/nm)| 0| 2400|
+|Frequency Offset (GHz)|-3.6|3.6|
+|peak DGD (ps)| 0| 28|
+|peak PDL (dB)| 0| 3.5|
+|SOP (krad/s)| 0| 50|
+|Case Temperature ($^{o}$C) | |75 |
+|Laser Temperature ($^{o}$C)| |75 |
+| EVM| | |
+
+
+
 - get_VDM
 
 ```get_VDM_page``` function uses ```VDM_TYPE``` dictionary above. It parses all the VDM items defined in the dictionary within a certain VDM page and returns both VDM monitor values and four threshold values related to this VDM item. ```get_VDM``` function combines VDM items from all VDM pages.