There are two common formats used for storing the orbital elements of a satellite. The two line format is used by NASA and NORAD in their prediction reports. The AMSAT format is more descriptive and is used for amateur radio.
Data generated by NORAD and distributed by NASA is distrbuted in this compact format. The data is designed to be used with an accurate model called SGP4. Each record for a satellite consists of three lines, the first with the satellite's name, and the next two with the data in a fixed text format.
There are several similiar formats that are called the "AMSAT" format, although there is an official specification. This format is designed to be read and edited by humans, and for this reason, each field has a descriptive tag, and the organization of data isn't as rigid as in the TLE format.
There are problems with converting from the AMSAT format into the two-line format due to considerations of the accuracy of the prediction models. If you are concerned about accuracy, do not convert between the AMSAT and TLE formats, and use the SGP4 model for NORAD element sets.