[Xpert]what's exact meaning of request length

[Martin Ding]

I recently study request but meet more problem. Now the meaning of request length puzzled me. For example, the request of X_ImageText8   typedef struct {     CARD8 reqType;     BYTE nChars;     CARD16 length B16;     Drawable drawable B32;     GContext gc B32;     INT16 x B16, y B16; } xImageTextReq;   I can intercept the request, and as document said, length means the request length, but it is related to the string length(nChars). During the test, request length can be 5, 18, 19, or 20 or others. as xImageTextReq struct occupy 16 bytes, how can I explain 5. Could you tell me the meaning about request length? Is it related to the struct? if not, how explain the member in struct which may be gotten from the request?