**4. Conclusions**

Motivated by the recent work of Popov and Vinogradov [4], we have examined the relevant conditions for usual and strange waves, particularly for scalar pulses. General necessary and sufficient conditions for scalar and electromagnetic field pulses possessing spatiotemporal coupling to be "usual" or "strange" have been derived in the time domain, and their application has been illustrated. For various examples of luminal and rather peculiar subluminal and superluminal scalar waves, it has been shown that even if they are strange, the corresponding finite-energy electromagnetic fields constructed from the scalar fields from either a magnetic potential within the framework of a Coulomb gauge or a vector Hertz potential are usual. Finally, source-generated strange electromagnetic fields have been reported.

**Author Contributions:** Investigation, P.S. and I.M.B.; writing—original draft preparation, P.S. and I.M.B.; writing—review and editing, P.S. and I.M.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding. **Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
