PDPs, or Professional Development Points, are used by teachers for "self-accounting" purposes. Principals and other administrators rely on teachers to provide documentation that supports their professional educational activities and an Individual Professional Development Plan (IPDP) that was previously approved (signed by teacher and principal).  Each IPDP contains goals and objectives to which each PDP can be linked.  Goals are met through products that were accomplished by attendance at conferences, seminars, workshops and other sessions where instruction and information were provided.  Session providers assign certain values of PDPs according to the number of hours attended or used for development of a project.  Usually, 10 PDPs toward a teacher's goals is considered a group value for a product.  (That is why so many workshops are for 10 hours.)

If you have a technology, literature, or information literacy goal, sessions at the conference could promote that goal, the project completion is up to you.  For example, showcasing your new webpage or blog for a department meeting sould be the culmination of several work sessions with colleagues and attendance at a conference session or two.  Attending author sessions might be part of your goal to improve your knowledge of YA literature.  As a product, you create a book discussion group, or a series of booktalks for classes.

When MSLA awards professional development points, they serve as a value of time for the attendance of MSLA's professional offerings.  There are many ways to accrue PDPs because the value to our profession as librarians deserves a value. Writing for the MSLA Forum, exhibiting at the Conference Exploratorium, or serving on an MSLA committee all serve our students and school communities and are products that can be appreciated by school and district administration.  That is not to say that the district has its own guidelines for evaluating and assigning PDPs.  Each district can plan, assess, and approve professional development as it wishes, but the Massachusetts Department of Elementary and Secondary Education has guidelines for teachers to keep track of their own IPDPs and Professional Development Points, and you must have a product.  In this way, your administrators can link your conference attendance directly to your product.

From the DESE webpage http://www.doe.mass.edu/recert/qa.html , the Recertification Guidelines state:

PDPs will not be awarded for attendance at a professional conference.
Are there any instances where conference participants can earn PDPs?
Yes, educators may receive PDPs for attendance at a professional conference only in the following instances:

•Registered professional development providers may award PDPs for conference attendance when educators participate in a conference for 10 hours or more on a topic with an observable demonstration of learning that could include a written product or other product that can be documented. Registered providers should issue Certificates of Attendance when educators participate in a conference that is less
than 10 hours in a topic.

•Districts may award PDPs to educators for conference attendance after the successful completion of a professional conference (as evidenced by a Certificate of Attendance) with follow-up activities at the district level that combined with conference attendance total 10 hours or more. Follow-up activities at the district level must include an observable demonstration of learning that could include a written
product or other product that can be documented.

•Educators are eligible to receive 30 PDPs from the conference provider or district the first time they make a presentation at a professional conference in a five-year renewal cycle.