A certificate may be represented in Base64; an example of which is given below:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

How to view a certificates attributes:

Certificate public key:
openssl x509 -in server.cer -noout -subject -issuer -startdate -enddate

Certificate request:
openssl req -in server.cer -noout -subject