anchor.diff:  "y13m",1,"2pure2","Partial fractions and algebraic division","learn","edexcel-schemes/m/2pure2.pdf"
   "y13m",1,"2pure5","Binomial expansion, advanced","learn","edexcel-schemes/m/2pure5.pdf"
   "y13m",1,"2stats1","Correlation and regression, advanced","learn","edexcel-schemes/m/2stats1.pdf"
  -"y13m",1,"test-y13ht1","HT1 test, ready for 0123 in Oct","assess",
  +"y13m",1,"test-y13ht1","HT1 test, ready for 0123 in Oct","assess","assessments/maths-y13-ht1.docx"
   "y13m",1,"2mech4","Moments","learn","edexcel-schemes/m/2mech4.pdf"
   "y13m",1,"2mech5","Resolving forces, friction","learn","edexcel-schemes/m/2mech5.pdf"
   "y13m",2,"2pure6","More trigonometry (radians, identities)","learn","edexcel-schemes/m/2pure6.pdf"
   "y13m",2,"2pure8","Differentiation, advanced","learn","edexcel-schemes/m/2pure8.pdf"
   "y13m",2,"2stats2","More probability","learn","edexcel-schemes/m/2stats2.pdf"
  -"y13m",2,"test-y13ht2","HT2 test, late Nov","assess",
  +"y13m",2,"test-y13ht2","HT2 test, late Nov","assess","assessments/maths-y13-ht2.docx"
   "y13m",2,"2mech6","Projectiles","learn","edexcel-schemes/m/2mech6.pdf"
   "y13m",3,"test-y13-mock","January Mock","assess",
   "y13m",3,"2stats3","Normal distribution","learn","edexcel-schemes/m/2stats3.pdf"
  
positive.code: "y12m",1,"1pure1","GCSE Algebra, discriminant, sketching curves","learn","edexcel-schemes/m/1pure1.pdf"
  "y12m",1,"1pure2","Coordinate geometry in the (x, y) plane","learn","edexcel-schemes/m/1pure2.pdf"
  "y12m",1,"1pure8","Exponentials & logarithms","learn","edexcel-schemes/m/1pure8.pdf"
  "y12m",1,"test-y12ht1","HT1 test","assess","assessments/maths2017-ht1.docx"
  "y12m",2,"1pure3","Proofs, factor theorem, binomimal expansion","learn","edexcel-schemes/m/1pure3.pdf"
  "y12m",2,"1stats1","Statistical sampling","learn","edexcel-schemes/m/1stats1.pdf"
  "y12m",2,"1stats2","Data presentation and interpretation","learn","edexcel-schemes/m/1stats2.pdf"
  "y12m",2,"test-ht2","HT2 test ready for Y12 SCE","assess","assessments/maths2017-ht2.docx"
  "y12m",2,"1mech6","Quantities and units in mechanics","learn","edexcel-schemes/m/1mech6.pdf"
  "y12m",2,"1mech7","Kinematics 1 (constant acceleration)","learn","edexcel-schemes/m/1mech7.pdf"
  "y12m",2,"1pure4","Trigonometry","learn","edexcel-schemes/m/1pure4.pdf"
  "y12m",3,"test-jan-y12mock","Mock exam - trimmed AS paper","assess",
  "y12m",3,"1pure5","Vectors (2D)","learn","edexcel-schemes/m/1pure5.pdf"
  "y12m",3,"1stats3","Probability","learn","edexcel-schemes/m/1stats3.pdf"
  "y12m",3,"1stats4","Statistical distributions","learn","edexcel-schemes/m/1stats4.pdf"
  "y12m",3,"test-y12ht3","HT3 test","assess",
  "y12m",4,"1pure6","Differentiation","learn","edexcel-schemes/m/1pure6.pdf"
  "y12m",4,"1pure7","Integration","learn","edexcel-schemes/m/1pure7.pdf"
  "y12m",4,"1stats5","Hypothesis testing","learn","edexcel-schemes/m/1stats5.pdf"
  
negative.code: "y12fm",6,"2core1","DeMoivre's Theorem, nth complex roots","learn","edexcel-schemes/fm/2core1.pdf"
  "y13fm",1,"2dec10","Critical path 2: resource histograms and scheduling","learn","edexcel-schemes/fm/2dec10.pdf"
  "y13fm",1,"2mech4","Momentum and impulse in 2D","learn","edexcel-schemes/fm/2mech4.pdf"
  "y13fm",1,"test-y13ht1","HT1 test, ready for 0123 in Oct","assess","assessments/fm-y13-ht1.docx"
  "y13fm",2,"2core2","Hyperbolic functions","learn","edexcel-schemes/fm/2core2.pdf"
  "y13fm",2,"2core3","Polar co-ordinates","learn","edexcel-schemes/fm/2core3.pdf"
  "y13fm",2,"2mech6","Collisions in 2D","learn","edexcel-schemes/fm/2mech6.pdf"
  