The IGS task force for a standardized format of GNSS satellite product combination statistics

GNSS precise point positioning (PPP) requires precise satellite orbit, clock and code/phase bias products. The International GNSS Service (IGS) has been operationally providing such high-precision valuables in support of science and society. Since the IGS encompasses various analysis centers (ACs), it is usual practice to compare these solutions to provide feedback to the ACs and also to combine them to generate the official IGS products with higher stability, reliability, completeness, and robustness. Under the current IGS framework, the AC Coordinator (ACC, acc.igs.org) manages orbit and clock combinations, while the Ionosphere Committee (IC, igs.org/wg/ionosphere) and Reference Frame Committee (RFC, igs.org/wg/reference-frame) are responsible for ionosphere products and station coordinates. Meanwhile, the newly established Wuhan Combination Center (WCC, igs.org/wg/wcc) is acting as an experimental alternative to augment the legacy combination procedures.  Usually, a “summary” file containing the combined statistical results is generated to facilitate contributions from ACs. However, such a summary file format shows a few limitations, e.g., failure in complying with a dedicated format standard, no statistics for the combined code/phase bias products and insufficient quality evaluation indices, such as anomalous satellites, outlier clocks, and so on. Consequently, these limitations hinder automated parsing and diminish human interpretability of the summary results. During the 2025 Governing Board meeting in Rimini, the IGS formed a task force led by WCC in collaboration with ACC and the Infrastructure Committee, to define a format standard to address the limitations of the traditional summary file. Specifically, the primary objectives of the task force are threefold: first, to establish a format that enables ACs to easily inspect their products artifacts; second, to establish a format that allows PPP and other users to easily exclude outlier products; and third, to develop auxiliary scripts for plotting the combination statistics. The proposed format is expected to support ACs in troubleshooting and verification of their products, along with downstream users for both network and PPP processing, e.g., by enabling consistent quality screening and exclusion of outlier products.