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+#The Nerv IO Package#
+Part of the [Nerv](../README.md) toolkit.
+
+##Description##
+There are four classes in to deal with chunk data, which are __nerv.ChunkFile__, __nerv.ChunkFileHandle__, __nerv.ChunkInfo__, __nerv.ChunkData__. Below is the underlying C structs.
+```
+typedef struct ChunkFileHandle {
+    FILE *fp;
+} ChunkFileHandle;
+
+typedef struct ChunkInfo {
+    off_t offset, length;
+} ChunkInfo;
+
+typedef struct ChunkData {
+    FILE *fp;
+    char *data;
+} ChunkData;
+```
+
+##Methods##
+* __ChunkFile ChunkFile.\_\_init(string mode, string fn)__  
+`mode` can be `r` or `w`, for reading or writing a file.
+
+##Developer Notes##
+In __Nerv.io__, a returned(by `ChunkFile.__init`) __nerv.ChunkFile__ will have a member `handle`, which is a __nerv.ChunkFileHandle__.  
+\ No newline at end of file