In the field of engineering, can GRE General test score be substituted with GRE Math score? In the field of engineering, can GRE General test score be substituted with GRE Math score?

Suppose a US university requires GRE general test score for PhD program, if an applicant sends GRE Math score, will that be enough?
Pretty much all programs will reject your application without consideration if you do not submit everything they request.  Some places are flexible; they may be willing to accept either test score.  (Some of the department at my university, including my department, are willing to take any one relevant score.)  However, such programs will almost always state this explicitly in their graduate application guidelines.  If you think a program might be willing to accept the substitution, you can always contact their director of graduate admissions or director of graduate studies and ask.  Chances are strongly against their saying yes, but it probably will not hurt your chances if you ask.