diff --git a/api.md b/api.md
index b7fd430..0d74425 100644
--- a/api.md
+++ b/api.md
@@ -52,6 +52,21 @@ initialize an *ExhaleEncAPI* object for encoding and allocate dynamic object mem
 * *audioConfigBuffer*: pointer to an unsigned 8-bit integer buffer to which the ASC data will be written. The buffer must be at least 16 bytes large. May be `NULL`, in which case no ASC is generated.
 * *audioConfigBytes*: pointer to a single unsigned 32-bit integer to which the byte-size of the ASC data is written. Optional parameter, may be `NULL`, in which case the size information is discarded.
 
+**Since exhale 1.0.1**:
+If, when calling this function, the integer pointed to by *audioConfigBytes* is nonzero, that
+integer is interpreted as program *loudnessInfo( )* payload according to [ISO/IEC 23003-4](https://www.iso.org/standard/75930.html), Dynamic 
+Range Control (DRC), and included in the *UsacConfig( )* data generated by this function. The
+bits of the nonzero integer pointed to by *audioConfigBytes* are interpreted as follows:
+
+| Bit Offset | Number of Bits | Syntax Element (Specification Table in ISO/IEC 23003-4)       |
+|------------|----------------|---------------------------------------------------------------|
+|      31-30 |              2 | not used, should equal 0                                      |
+|      29-18 |             12 | *bsSamplePeakLevel*, peak level of audio program (Table A.46) |
+|      17-14 |              4 | *methodDefinition*, must be between 1 and 9 (Table A.49)      |
+|      13-6  |              8 | *methodValue*, loudness level of audio program (Table A.48)   |
+|      5-2   |              4 | *measurementSystem*, must be between 1 and 6 (Table A.50)     |
+|      1-0   |              2 | *reliability*, should equal 3, should not equal 0 (Table A.51)|
+
 **Return value**
 
 zero (0) upon success, or nonzero (1-255 or 65535) in case of an error or if the *exhaleEnc* pointer is `NULL`