There is no ASCII format. This term refers to a whole group of formats in which sample values, time, and other data are stored in ASCII-encoded text. Although it is easy to read and understand the content of the file, its correct loading requires the formalization of the record. Therefore, the two plugins read slightly different text formats.

IRIS ASCII

This is the format proposed for ASCII data by IRIS. A full description of the format can be found e.g. at https://ds.iris.edu/ds/nodes/dmc/data/formats/simple-ascii/.

Simple ASCII

It is a simple ASCII format in which data is stored in two columns. The first column contains the sample times in seconds since January 1, 1970, and the second column contains the sample values in m/s.