Quotations from the ACRIM website...
The PMOD composite approach uses a different subset of the satellite TSI database, the ERBS/ERBE ACRIM gap ratio and modifies published Nimbus7/ERB and ACRIM1 results, to conform them to the predictions of TSI proxy models [Frohlich & Lean, 1998]. The sparse ERBS/ERBE data required the PMOD model to use about 90% interpolated data to compute their ACRIM gap ratio.
There are a number of differences between the ACRIM and PMOD composites but the most important is the trend during solar cycles 21 - 23. The absence of a trend in the PMOD composite and any composite based on the ERBS/ERBE ACRIM gap ratio has been shown to be an artifact of uncorrected degradation of ERBE results during the gap (See Fig. 4). http://www.acrim.com/images/earth_obs_ACRIM_Gap_4p.jpg
Note that the ERBE data has the opposite % Variation slope of NIMBUS 7 and GSSN during the ACRIM gap, which is what the PMOD dataset is based off of. This shows that the ERBE/ERBS dataset needs to be corrected, which the PMOD dataset did not do.