period structure icon in sap planning book

Hi There,

In DP planning Book when I click on "Header On/Off" Icon (Hat like Icon- which is left to Refresh Icon) I am getting  Period structure Icon and Header setting icon.

In SNP planning Book when I click on "Header On/Off" Icon (Hat like Icon- which is left to Refresh Icon) I am getting only Header setting icon.There is no Period structure Icon.

So kindly help me to find the Period structure Icon.

Thanks,

Ayaskant