Coordinate transformations are defined by, what in PROJ terminology is known as, “proj-strings".
1.what in PROJ terminology is known as, 是名词性从句？
2.proj-strings 是what....从句与Coordinate transformations are defined by 主句 的公共部分吗？能具体剖析一下吗？
1 what in PROJ terminology is known as 是个不完整的名词性从句，介词as缺少宾语。
2 是的，what....从句与Coordinatetransformations are defined by 共用名词proj-strings。
这个句子等于下面二个句子：
Coordinate transformations are defined by what inPROJ terminology is known as “proj-strings".
Coordinate transformations are defined by“proj-strings".
第一句介词by的宾语为what引导的名词性从句（名词性关系分句）。第二句介词by的宾语为名词“proj-strings"。作者原句中的二个逗号等于括号，表示这部分可有可无。
