Change:
2. <del> The protocol is executed by a large set of clients and a small set of servers.  Servers are referred to as . Each client's input to the protocol is a set of measurements (e.g., counts of some user behavior).  Given the input set of measurements "x_1, ..., x_n" held by "n" users, the goal of a protocol for privacy preserving measurement is to compute "y = F(p, x_1, ..., x_n)" for some function "F" while revealing nothing else about the measurements. </del> <ins> The protocol is executed by a large set of Clients and a small set of servers.  Servers are referred to as "Aggregators".  Each Client's input to the protocol is its measurement (or set of measurements, e.g., counts of some user behavior).  Given the input set of measurements "x_1, ..., x_n" held by "n" users, the goal of DAP is to compute "y = F(p, x_1, ..., x_n)" for some function "F" while revealing nothing else about the measurements.  We call "F" the "aggregation function". </ins> This protocol is extensible and allows for the addition of new cryptographic schemes that implement the VDAF interface specified in VDAF.  Candidates include: <del> Prio3, which allows for aggregate statistics such as sum, mean, histograms, etc.  This class of VDAFs is based on Prio CGB17 and includes improvements described in BBCGGI19. </del> <ins> Prio3 (VDAF), which allows for aggregate statistics such as sum, mean, histograms, etc. </ins> <del> Poplar1, which allows for finding the most popular strings among a collection of clients (e.g., the URL of their home page) as well as counting the number of clients that hold a given string.  This VDAF is the basis of the Poplar protocol of BBCGGI21, which is designed to solve the heavy hitters problem in a privacy </del> <ins> Poplar1 (VDAF), which allows for finding the most popular strings uploaded by a set of Clients (e.g., the URL of their home page) as well as counting the number of Clients that hold a given string. This VDAF is the basis of the Poplar protocol of BBCGGI21, which is designed to solve the heavy hitters problem in a privacy </ins> preserving manner. <del> This protocol is designed to work with schemes that use secret sharing.  Rather than sending its input in the clear, each client shards its measurements into a sequence of and sends an input share to each of the aggregators.  This provides two important properties: </del> <ins> VDAFs rely on secret sharing to protect the privacy of the measurements.  Rather than sending its input in the clear, each client shards its measurements into a sequence of "input shares" and sends an input share to each of the Aggregators.  This provides two important properties: </ins> <del> It is impossible to deduce the measurement without knowing </del> <ins> Given only a subset of the input shares, it is impossible to deduce the plaintext measurement from which they were generated. </ins> <del> of the shares. It allows the aggregators to compute the final output by first aggregating up their measurements shares locally, then combining the results to obtain the final output. </del> <ins> It allows the Aggregators to compute the aggregation function by first aggregating up their input shares locally into "aggregate shares", then combining the aggregate shares into the aggregate result. </ins> 2.1. <del> The overall system architecture is shown in pa-topology. </del> <ins> The overall system architecture is shown in dap-topology. </ins> [[OPEN ISSUE: This shows two helpers, but the document only allows one for now.  https://github.com/ietf-wg-ppm/draft-ietf-ppm-dap/

Discussion:
Based on .
NAME can you please rebase? Some of the changes we improved on in now appear here.
Rebased.