The following XDb1 example models things with variable properties. See
www.xdb1.com/Example/Ex109.asp for additional info.

Data to Model
-------------
wig1's color is red.
wig2's color is red, green AND texture is soft AND material is nylon.
wig3's texture is soft AND material is jute.

coat1's color is red.
coat2's texture is soft AND material is cotton.
coat3's color is green AND texture is smooth, supple.

Queries
-------
Find all things with attributes color and texture.
Print the property and values of all wigs.

void Example109()
{
// Create wig class
int* pWig = T_create();
T_relate(&pWig, rCls, &pThing_g);
T_Name_relate(&pWig, _T("wig"));

// Create coat class
int* pCoat = T_create();
T_relate(&pCoat, rCls, &pThing_g);
T_Name_relate(&pCoat, _T("coat"));

// Create color class
int* pColor = T_create();
T_relate(&pColor, rCls, &pThing_g);
T_Name_relate(&pColor, _T("color"));

// Create texture class
int* pTexture = T_create();
T_relate(&pTexture, rCls, &pThing_g);
T_Name_relate(&pTexture, _T("texture"));

// Create material class
int* pMaterial = T_create();
T_relate(&pMaterial, rCls, &pThing_g);
T_Name_relate(&pMaterial, _T("material"));

// Create wig1
// Its color is red.
int* pWig1 = T_create();
T_relate(&pWig1, rCls, &pWig);
T_Name_relate(&pWig1, _T("wig1"));
T_Val_relate(&pWig1, &pColor, _T("red"));

// Create wig2
// Its color is red, green
// AND texture is soft AND material is nylon.
int* pWig2 = T_create();
T_relate(&pWig2, rCls, &pWig);
T_Name_relate(&pWig2, _T("wig2"));
T_Val_relate(&pWig2, &pColor, _T("red"));
T_Val_relate(&pWig2, &pColor, _T("green"));
T_Val_relate(&pWig2, &pTexture, _T("soft"));
T_Val_relate(&pWig2, &pMaterial, _T("nylon"));

// Create wig3
// Its texture is soft AND material is jute.
int* pWig3 = T_create();
T_relate(&pWig3, rCls, &pWig);
T_Name_relate(&pWig3, _T("wig3"));
T_Val_relate(&pWig3, &pTexture, _T("soft"));
T_Val_relate(&pWig3, &pMaterial, _T("jute"));

// Create coat1
// Its color is red.
int* pCoat1 = T_create();
T_relate(&pCoat1, rCls, &pCoat);
T_Name_relate(&pCoat1, _T("coat1"));
T_Val_relate(&pCoat1, &pColor, _T("red"));

// Create coat2
// Its texture is soft AND material is cotton.
int* pCoat2 = T_create();
T_relate(&pCoat2, rCls, &pCoat);
T_Name_relate(&pCoat2, _T("coat2"));
T_Val_relate(&pCoat2, &pTexture, _T("soft"));
T_Val_relate(&pCoat2, &pMaterial, _T("cotton"));

// Create coat3
// Its color is green AND texture is smooth, supple.
int* pCoat3 = T_create();
T_relate(&pCoat3, rCls, &pCoat);
T_Name_relate(&pCoat3, _T("coat3"));
T_Val_relate(&pCoat3, &pColor, _T("green"));
T_Val_relate(&pCoat3, &pTexture, _T("smooth"));
T_Val_relate(&pCoat3, &pTexture, _T("supple"));

// Create a relational expression
// to find things related to color AND texture
TCHAR sExpr[kNmSz_g+1] = _T("((color)) ((texture))");

// Prepare relational expression
#define aSz 255
int* pExpr[aSz+1] = {NULL};
if (X_parse_r(sExpr, pExpr, aSz)) {return;}

// Loop thru distinct things satisfying expression
// and print thier full name.
// The loop below prints the following three lines
// "((wig))(wig2)(((color))(red))(((color))(green))(( (texture))(soft))(((material))(nylon))"
// "((coat))(coat3)(((color))(green))(((texture))(smo oth))(((texture))(supple))"
while (int* pT=X(pExpr, TRUE)){
TCHAR sName[kNmSz_g+1] = _T("");
T_Name_get(pT, sName, kNmSz_g, TRUE);
TRACE(_T("%s\n"), sName);
}

// Given wig1, print its info
// Prints "((wig))(wig1)(((color))(red))"
TCHAR sName[kNmSz_g+1] = _T("");
T_Name_get(pWig1, sName, kNmSz_g, TRUE);
TRACE(_T("%s\n"), sName);

// Given wig2, print its info
// Prints "((wig))(wig2)(((color))(red))(((color))(green))(( (texture))(soft))(((material))(nylon))"
_tcscpy(sName, _T(""));
T_Name_get(pWig2, sName, kNmSz_g, TRUE);
TRACE(_T("%s\n"), sName);

// Given wig3, print its properties/values using alternate method
// "wig3's name is wig3."
// "wig3's texture is soft."
// "wig3's material is jute."
// Loop thru wig3's relations
int* pR = pWig3;
while (*(++pR)){
// If relation is to a value
if (rIs == R_Type_get(pR)){
// Get value
int* pVal = R_Dest(pR);

// Get value's Cls (same a property)
int* pProp = T_R_Xth(pVal, rCls);

// Print "thingX's propY is valX."
TCHAR sTh[kNmSz_g+1] = _T("");
T_Name_get(pWig3, sTh, kNmSz_g);

TCHAR sProp[kNmSz_g+1] = _T("");
T_Name_get(pProp, sProp, kNmSz_g);

TCHAR sVal[kNmSz_g+1] = _T("");
T_Name_get(pVal, sVal, kNmSz_g);

TCHAR sSent[3*kNmSz_g+1] = _T("");
_stprintf(sSent, _T("%s's %s is %s."), sTh, sProp, sVal);
TRACE(_T("%s\n"), sSent);
}
}
}