diff --git a/README.md b/README.md
index c49b870a..d6ce7649 100644
--- a/README.md
+++ b/README.md
@@ -545,6 +545,9 @@ cs:listen(5683)
 myvar=1
 cs:var("myvar") -- get coap://192.168.18.103:5683/v1/v/myvar will return the value of myvar: 1
 
+all='[1,2,3]'
+cs:var("all", coap.JSON) -- sets content type to json
+
 -- function should tack one string, return one string.
 function myfun(payload)
   print("myfun called")
diff --git a/app/coap/coap.h b/app/coap/coap.h
index 3862f57b..f47123f2 100644
--- a/app/coap/coap.h
+++ b/app/coap/coap.h
@@ -116,6 +116,10 @@ typedef enum
     COAP_CONTENTTYPE_NONE = -1, // bodge to allow us not to send option block
     COAP_CONTENTTYPE_TEXT_PLAIN = 0,
     COAP_CONTENTTYPE_APPLICATION_LINKFORMAT = 40,
+    COAP_CONTENTTYPE_APPLICATION_XML = 41,
+    COAP_CONTENTTYPE_APPLICATION_OCTET_STREAM = 42,
+    COAP_CONTENTTYPE_APPLICATION_EXI = 47,
+    COAP_CONTENTTYPE_APPLICATION_JSON = 50,
 } coap_content_type_t;
 
 ///////////////////////
@@ -156,6 +160,7 @@ struct coap_luser_entry{
     // char name[MAX_SEGMENTS_SIZE+1];         // +1 for string '\0'
     const char *name;
     coap_luser_entry *next;
+    int content_type;
 };
 
 struct coap_endpoint_t{
diff --git a/app/coap/endpoints.c b/app/coap/endpoints.c
index a54b1235..00705f93 100644
--- a/app/coap/endpoints.c
+++ b/app/coap/endpoints.c
@@ -64,14 +64,14 @@ static int handle_get_variable(const coap_endpoint_t *ep, coap_rw_buffer_t *scra
                     {
                         n = lua_gettop(h->L);
                         lua_getglobal(h->L, h->name);
-                        if (!lua_isnumber(h->L, -1)) {
-                            NODE_DBG ("should be a number.\n");
+                        if (!lua_isnumber(h->L, -1) && !lua_isstring(h->L, -1)) {
+                            NODE_DBG ("should be a number or string.\n");
                             lua_settop(h->L, n);
                             return coap_make_response(scratch, outpkt, NULL, 0, id_hi, id_lo, &inpkt->tok, COAP_RSPCODE_NOT_FOUND, COAP_CONTENTTYPE_NONE);
                         } else {
                             const char *res = lua_tostring(h->L,-1);
                             lua_settop(h->L, n);
-                            return coap_make_response(scratch, outpkt, (const uint8_t *)res, c_strlen(res), id_hi, id_lo, &inpkt->tok, COAP_RSPCODE_CONTENT, COAP_CONTENTTYPE_TEXT_PLAIN);
+                            return coap_make_response(scratch, outpkt, (const uint8_t *)res, c_strlen(res), id_hi, id_lo, &inpkt->tok, COAP_RSPCODE_CONTENT, h->content_type);
                         }
                     }
                 } else {
@@ -198,10 +198,10 @@ static int handle_get_id(const coap_endpoint_t *ep, coap_rw_buffer_t *scratch, c
     return coap_make_response(scratch, outpkt, (const uint8_t *)(&id), sizeof(uint32_t), id_hi, id_lo, &inpkt->tok, COAP_RSPCODE_CONTENT, COAP_CONTENTTYPE_TEXT_PLAIN);
 }
 
-coap_luser_entry var_head = {NULL,NULL,NULL};
+coap_luser_entry var_head = {NULL,NULL,NULL,0};
 coap_luser_entry *variable_entry = &var_head;
 
-coap_luser_entry func_head = {NULL,NULL,NULL};
+coap_luser_entry func_head = {NULL,NULL,NULL,0};
 coap_luser_entry *function_entry = &func_head;
 
 const coap_endpoint_t endpoints[] =
diff --git a/app/modules/coap.c b/app/modules/coap.c
index 1d496e5f..7dadb06d 100644
--- a/app/modules/coap.c
+++ b/app/modules/coap.c
@@ -429,6 +429,7 @@ static int coap_regist( lua_State* L, const char* mt, int isvar )
 {
   size_t l;
   const char *name = luaL_checklstring( L, 2, &l );
+  int content_type = luaL_optint(L, 3, COAP_CONTENTTYPE_TEXT_PLAIN);
   if (name == NULL)
     return luaL_error( L, "name must be set." );
 
@@ -457,6 +458,7 @@ static int coap_regist( lua_State* L, const char* mt, int isvar )
 
   h->L = L;
   h->name = name;
+  h->content_type = content_type;
 
   NODE_DBG("coap_regist is called.\n");
   return 0;  
@@ -585,6 +587,12 @@ const LUA_REG_TYPE coap_map[] =
 #if LUA_OPTIMIZE_MEMORY > 0
   { LSTRKEY( "CON" ), LNUMVAL( COAP_TYPE_CON ) },
   { LSTRKEY( "NON" ), LNUMVAL( COAP_TYPE_NONCON ) },
+  { LSTRKEY( "TEXT_PLAIN"), LNUMVAL( COAP_CONTENTTYPE_TEXT_PLAIN ) },
+  { LSTRKEY( "LINKFORMAT"), LNUMVAL( COAP_CONTENTTYPE_APPLICATION_LINKFORMAT ) },
+  { LSTRKEY( "XML"), LNUMVAL( COAP_CONTENTTYPE_APPLICATION_XML ) },
+  { LSTRKEY( "OCTET_STREAM"), LNUMVAL( COAP_CONTENTTYPE_APPLICATION_OCTET_STREAM ) },
+  { LSTRKEY( "EXI"), LNUMVAL( COAP_CONTENTTYPE_APPLICATION_EXI ) },
+  { LSTRKEY( "JSON"), LNUMVAL( COAP_CONTENTTYPE_APPLICATION_JSON) },
 
   { LSTRKEY( "__metatable" ), LROVAL( coap_map ) },
 #endif
@@ -609,6 +617,12 @@ LUALIB_API int luaopen_coap( lua_State *L )
   // Module constants  
   MOD_REG_NUMBER( L, "CON", COAP_TYPE_CON );
   MOD_REG_NUMBER( L, "NON", COAP_TYPE_NONCON );
+  MOD_REG_NUMBER( L, "TEXT_PLAIN", COAP_CONTENTTYPE_TEXT_PLAIN );
+  MOD_REG_NUMBER( L, "LINKFORMAT", COAP_CONTENTTYPE_APPLICATION_LINKFORMAT );
+  MOD_REG_NUMBER( L, "XML", COAP_CONTENTTYPE_APPLICATION_XML);
+  MOD_REG_NUMBER( L, "OCTET_STREAM", COAP_CONTENTTYPE_APPLICATION_OCTET_STREAM);
+  MOD_REG_NUMBER( L, "EXI", COAP_CONTENTTYPE_APPLICATION_EXI);
+  MOD_REG_NUMBER( L, "JSON", COAP_CONTENTTYPE_APPLICATION_JSON);
 
   n = lua_gettop(L);