CBSubs 1.2 has implemented more customization for "This calendar..." type dates. Now for example allowing you to select what month "This calendar year" ends on; no longer static to December for example. We're gradually adding more customization to plan durations when possible.

Yes, the documentation missed this new feature (too many in CBSubs 1.2).

I have already fixed for next version with the following text:

• Manual renewal extends expiration date as follows: [initial value: ‘Renewal starts at expiration date or at payment date – whichever happens last (allows free gap)’]
This drop-down parameter field allows you to specify how CBSubs™ should handle renewals of plan and it has the following options:
o ‘Renewal starts at expiration date or at payment date – whichever happens last (allows free gap)’
This is the default setting. To understand the mode of operation that this option specifies the following example is provided. If the expiration date of a one year (12 month) plan is 01-02-2011 (February 1st) and the user renews the subscription on 08-02-2011 (one week after the expiration date), then the new expiration date will be 08-02-2012 (exactly 12 months after payment). If the user renews on 15-01-2011 (before expiration), then the new expiration date will be 01-02-2012 (exactly 12 months after normal expiration). Thus there is a gap if user renews after expiration.
o ‘Renewal extends expiration date (without gap or overlap)’
Working off the previous example, late renewal will extend the original expiration date by 12 months, so it will be set to 01-02-2012. Early renewal will have the exact same result. This case can be used for club membership use cases.
o ‘Renewal starts at payment date (allows overlap or free gap)’
The option will renew the plan starting at payment date. This means that in our previous example, late renewal will result in a new expiration date of 08-02-2012 and an early renewal action would give a new expiration date of 15-01-2012.
o ‘Renewal starts at expiration date or at payment date – whichever happens first (allow overlap but no free gap)’
This option will give an expiration date of 15-01-2012 is renewal payment happens on 15-01-2011 and a renewal date of 01-02-2011 is renewal payment happens on 08-02-2011.