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Two repeating FRB sources, FRB180916 (CHIME/FRB Collaboration, 2020a) andFRB121102 (Rajwade, et al., 2020, Cruces, et al., 2021) display periodicwindowed behavior (PWB) in the times of FRB detections. In PWB, events onlyoccur within a periodic window spanning some fraction of the period, but noevents may occur during many of the periods. During UT 2020 April 28, two peaksof a soft gamma burst (Li, et al., 2021) were identified with two FRB peaks(CHIME/FRB Collaboration, et al., 2020b) from soft gamma repeater (SGR)1935+2154. As SGRs are a type of magnetar, these observations establish a linkbetween at least some FRBs and magnetars. The analysis herein, which selectsthe period giving the minimum window fraction, shows PWB in this source's softgamma-ray emission. For 161 bursts from 2014 through 2020 from IPN(Interplanetary Network) instruments, a clearly resolved minimum in windowfraction vs. period occurs at a 231 +/- 9 day period, and 55 \% windowfraction. The data cover only 6 bursting episodes, however, the periodicityresult appears relatively robust: First, the IPN has excellent time coverageand is unlikely to miss bursts outside of these windows. Second, for variousdata subsets (with significantly less bursts), either the best or second bestmeasured period was consistent with 231 days, even in the sub-sample with therichest bursting episode removed. In addition, simulations show that even smallnumbers of uniform random bursts do not show PWB, and that the results are notdue to limited sampling. The apparent PWB could have alternative explanations;a firm conclusion of PWB would be evident, however, after the observation ofmore consistent episodes. If the periodicity of this SGR's bursts can beverified, and if similar behavior were observed in other repeating FRB sources,it might suggest a linkage between FRB and SGR burst mechanisms or emissionconditions.

Possible Periodic Windowed Behavior in SGR1935+2154 SGR Bursts